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/V8/J /V*.
A STUDY OF THE RELATIONSHIP BETWEEN THE INTENSITY
OF SHORT-RANGE AND MEDIUM-RANGE CAPACITY
MANAGEMENT AND THE EFFECTIVENESS OF
MANUFACTURING OPERATIONS
DISSERTATION
Presented to the Graduate Counci1 of the
North Texas State University in Partial
Fulfillment of the Requirements
For the Degree of
DOCTOR OF PHILOSOPHY
By
Joseph Yehudai, B.Sc., M.B.A.
Denton, Texas
May, 1988
Yehudai, Joseph, A Study of the Relationship Between
the Intensity of Short-Range and Medium-Range Capacity
Management and the Effectiveness of Manufacturing
Operations - Doctor of Philosophy (Production and Operations
Management), May, 1988, 188 pp., 46 tables, 15
illustrations, bibliography, 146 titles.
The objective of this study was to examine the
relationship between intensity of short-range and medium-
range capacity management and effectiveness of manufacturing
operations. Data were collected to test the null
hypothesis which stated that intensity of short-range and
medium-range capacity management does not influence
manufacturing ef fect i veness.
Intensity of short-range and medium-range capacity
management was indicated by the following variables: (1)
production standards; (2) priority determination; (3)
delivery dates determination; (4) material requirements
planning; (5) routing information; (6) capacity utilization;
and (7) backlog measurement.
Manufacturing effectiveness was indicated by the
following variables: (1) delivery dates performance; (2)
lead times; (3) subcontract work; (4) direct labor overtime;
(5) direct labor efficiency; (6) plant and equipment
utilization; and (7) work in process inventory.
The population selected to provide data for this study
is the manufacturing firms in the State of Texas with five
hundred or more employees. Over 42 percent of the eligible
firms responded to a six-page questionnaire.
Several multivariate techniques were utilized for data
analysis: (1) factor analysis; (2) canonical correlation
analysis; (3) bivariate correlation; (4) multiple linear
regression; (5) cross-tabulation; and (6) analysis of
variance.
The results of this research did not adequately
support the rejection of the null hypothesis. However, they
did definitely identify a distinct group of capacity
management intensity variables that influence manufacturing
effectiveness in specific cases.
Intensity variables were placed in three groups that
identified how influential they were over the effectiveness
measures. The most influential group included the
variables: production standards and material requirements
planning. The indication for the manufacturing manager is
to concentrate on improvements in these areas.
Effectiveness variables were also placed in three
groups that identified the level at which the variables were
influenced by the intensity variables. The highly
influenced group included plant and equipment utilization
and delivery dates performance.
TABLE OF CONTENTS
LIST OF TABLES vi
LIST OF ILLUSTRATIONS viii
Chapter
I. INTRODUCTION i
Background 1 Deindustrializaticm and Productivity Manufacturing Strategy Existing Approaches to Capacity Management
Research Research Objectives 8
Importance of the Study Hypothesis Definition of Variables
Methodology 11 The Data . Population and Sample Frame Questionnaire Development Analysis of the Data
II. REVIEW OF QUANTITATIVE APPROACHES 16
Aggregate Capacity Planning 17 Linear Cost Models Quadratic Cost Models General Cost Models Evaluation of Aggregate Capacity Models
III. REVIEW OF SUBJECTIVE APPROACHES 41
Capacity Planning 41 Aggregate Capacity Planning (ACP) Rough-cut Capacity Planning (RCCP) Capacity Requirements Planning (CRP)
Capacity Control 62 Lead Time Control Input/Output Control
Overview 68
IV. DATA COLLECTION SURVEY 69
Design of Questionnaire 69 Selection of Variables
i i i
Development of Questions Numerical Value Assignment Questionnaire Construction
Survey Implementation 71 Pilot Study
Questionnaire Mailing and Follow-Up Summary of Participants 72
V. SURVEY ANALYSIS 80
Factor Analysis 80
Factor Analysis Applications
Results and Conclusions
Canonical Correlation 101
Bivariate Correlation 103
Multiple Linear Regression 110
Cross-Tabulation 113
Analysis of Variance 141
Synthesis: Capacity Management Intensity . . 142
Production Standards
Prior i ty Determination
Delivery Dates Determination
Material Requirements Planning
Routing Information
Capaci ty Uti1ization
Back 1og Measurement
Total Intensity Score
Synthesis: Manufacturing Effectiveness . . . 147
Delivery Dates Performance
Lead Times
Subcontract Work
Direct Labor Overtime
Direct Labor Efficiency
Plant and Equipment Utilization
Work in Process Inventory
VI. SUMMARY AND CONTRIBUTION 152
Hypothesis 152 Intensity Variables . 152
Most Influential Moderately Influential Least Influential
Effectiveness Variables 153 Highly Influenced Moderate 1y Inf1uenced Least Influenced
Demographic Characteristics 155 Type of Operation Number of Employees Two-Digit Standard Industrial Code (SIC)
IV
Future Research 156
APPENDIX A 157
APPENDIX B 158
APPENDIX C 159
APPENDIX D l 6 0
APPENDIX E 166
APPENDIX F 167
APPENDIX G 173
APPENDIX H 178
BIBLIOGRAPHY 181
LIST OF TABLES
1. Questionnaire Rate of Return
2. Respondents Classified by a Two-Digit Standard Industrial Code
3. Respondents Classified by Number of Employees 4. Respondents Classified by Type of Operation 5. Value of Statistics for Intensity Variables 6. Value of Statistics for Effectiveness Variables 7. Fourteen-Variab1e Factor Analysis Correlation
Matrix
8. Seven Intensity Variables Factor Analysis Corre lation Matrix
9. Seven Effectiveness Variables Factor Analysis Correlation Matrix
10. Fourteen-Variable Unrotated Factor Loading Matrix
11. Seven Intensity Variables Unrotated Factor Load ings Matrix
12. Seven Effectiveness Variables Unrotated Factor Loadings Matrix
13. Fourteen-Variable Varimax Rotated Factor Load-ings Matrix
14. Seven Intensity Variables Varimax Rotated Facto Loadings Matrix
15. Seven Effectiveness Variables Varimax Rotated Factor Loadings Matrix
16. Summary Presentation of Factor Loadings . . . 17. Fourteen-Variable Rotated Loadings Listed by
Magnitude 18. Seven Intensity Variables Rotated Loadings
Listed by Magnitude 19. Seven Effectiveness Variables Rotated Loadings
Listed by Magnitude 20. First (Significant) Canonical Correlation Sta-
tistics and Coefficients 21. Pearson Correlation Coefficients . 22. Pearson Correlation Coefficients (SIC 34) . . 23. Pearson Correlation Coefficients (SIC 36) . . 24. Pearson Correlation Coefficients (SIC 39) . . 25. Multiple Linear Regression, Dependent Variable:
Delivery Dates Performance 26. Multiple Linear Regression, Dependent Variable:
Direct Labor Overtime . 27. Multiple Linear Regression, Dependent Variable:
Direct Labor Efficiency 28. Multiple Linear Regression, Dependent Variable:
Plant and Equipment Utilization
72
75 76 77 78
79
84
85
86
87
88
89
91
92
93
94
96
97
98
102
105 106 107
108
111
111
112
112 v 1
29. 30. 31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
Scores Classified by Number of Employees . . . Scores Classified by Type of Operation . . . . Respondents Classified by a Two-Digit Standard
Industrial Code and Number of Employees . . Respondents Classified by a Two-Digit Standard
Industrial Code and Type of Operation . . . Respondents Classified by Number of Employees
and Type of Operation One-Way Analys
Character i st Two-Way Analys
Character i s t Two-Way Analys
Character i st Two-Way Analys
s of cs s of cs s of cs s of
Variance by Demographic
Variance by Demographic
Variance by Demographic
Variance by Demographic Characteristics
Three-Way Analysis of Variance by Demographic Characteristics
Intermediary Statistics From Factor Analysis Determinant and Inverse of Fourteen-Variab1e Correlation Matrix
Intermediary Statistics From Factor Analysis Determinant and Inverse of Seven Intensity Variables Correlation Matrix
Intermediary Statistics From Factor Analysis Determinant and Inverse of Seven Effectiveness Variables Correlation Matrix
Transformation of Matrices . . . . Factor Score Coefficients Effectiveness Mean Scores Classified by Area of
Formal Education . Effectiveness Mean Scores Classified by Member
ship with Professional Associations Effectiveness Mean Scores of APICS Menbers
Classified by Those Who Hold a Certificate and Those Who Do Not
130
131
132
133
134
136
137
138
139
140
173
174
175
176
177
178
179
180
vx 1
LIST OF ILLUSTRATIONS
1. Distribution of scores standards variable
for the production
115 2. Distribution of scores
mination variable . . for the priority deter-
116 3. Distribution of scores for the de1i very dates
determination variable 117 4. Distribution of scores for the material
Requirements planning variable 118 5. Distribution of scores
mation variable - - . for the routing infor-
119 6. Distribution of scores
uti1ization variable f or the capaci ty
120 7. Distribution of scores
ment variable • . . . for the backlog measure-
121 8. Distribution of scores for the summation of the
seven capacity management intensity variables 122 9. Distribution of scores
performance var iab1e for the delivery dates
123 10. Distribution of scores
variable for the lead times
124 11. Distribution of scores
variable for the subcontract work
125 12. Distribution of scores
overtime variable . . for the direct labor
126
CO
• Distribution of scores efficiency variable .
for the direct labor
127 14. Distribution of scores for the plant and
equipment uti1ization variable 128
cn
• Distribution of scores for the work in process inventory variable
work in process
129
V I 1 1
CHAPTER I
INTRODUCTION
Background
In the last fifteen years numerous articles and books
have been written about the competitive vulnerability of
U.S. manufacturing companies. A major part of this vulnera-
bility arose out of the failure of these companies to
develop and manage their manufacturing capability effec-
* • . 1 tlve1y.
The following passage is an example of what can be
frequently found in today's business publications.
The notion that the U.S. is deindustrializing and becoming a nation of hamburger flippers, retail clerks and copying machine mechanics echoes through today's political and economic debate. High imports, plant closings and growing employment in service industries combine to generate the impression that the U.S. is losing its industrial base and its ability to manufac-ture goods that can compete in the world economy. "We can't afford to become a nation of video arcades, drive-in banks and McDonald's hamburger stands," warns Chrysler Corp. chairman Lee lacocca.
In order to reverse the current decline of U.S. manu-
facturing, the development of a proper manufacturing
strategy is essential. This strategy should be integrated
Elwood S. Buffa, Meeting the Competitive Challenge (Homewood, 111.: Richard D. Irwin, 1984), 2-19.
2 Mall Street Journal. 5 January 1987, 1.
with the overall corporate strategy. Capacity management is
an important part of any manufacturing strategy. This dis-
sertation will focus on capacity management that despite its
importance has not received appropriate research attention.
Deindustrialization and Productivity
In 1971, imports of manufactured goods into the U.S.
exceeded manufactured exports for the first time in almost a 3
century. This was a clear sign that U.S. manufacturing was
in decline. Although many American companies have fought
back successfully, the overall problem of deindustrializa-
tion and trade deficits remains.
While there are many causes that combine to create the
economic problems, one measure appears to summarize i t — t h e
productivity of the private sector. Productivity is a
concept that is hard to explain and measure. Typically it
is calculated by dividing a country's total "output,"
adjusted for inflation, by the number of labor hours re-
quired to create this output. Productivity has been used
for more than thirty years as a measure of private sector
vitality. It was also used as a measure of international
competitiveness. After rising at an average rate of approx-
imately 3 percent per year since World War II, U.S.
productivity stopped growing after 1976. Despite produc-
3 Robert H. Hayes and Steven C. Wheelwright,
Restoring Our Competitive Edge: Competing Through Manu-facturing (New York: John Wiley & Sons, 1984), 1.
tivity gain in 1982 and 1983, it has shown little evidence
of a sustained improvement- Studies of manufacturing firms
in the U.S. and abroad have revealed that the productivity
problem has been due less to foreign pressure and govern-
mental interference than to the way that U.S. managers have
4 guided their companies.
The use of productivity is not limited to labor
resources. It provides a useful way of measuring the effi-
ciency with which all resources are consumed during
production. Managers can increase productivity by using
existing capacity more effectively.^
Although the terms "priority" and "capacity" have been
in use for a long time, recent literature has brought
increased meaning to them. Monks presented his definition
of these terms as follows:
Priority, in a broad sense, is an ordering of goals or activities in accordance with an individual's or organi-zation's system of values. More specifically, priority refers to the ranking or importance of something--often materials. The measure of importance stems primarily from society, in other words, what customers want. Customer demands are, in turn, translated into purchase and production orders that must then be guided through operations until the desired good or service is produced. So customer orders have "priorities."
Capacity is a measure of an organization's ability to accomplish its prioritized goals, or more simply, the abilty to produce. In a production facility, this "ability" usually translates into having enough human and equipment capability and time to do the job.
4Ibid., 1-7.
^Ibid., 6.
0 Joseph G. Monks, Operations Management; Theory and
4
Monks maintained that a priority and capacity approach
may be useful for analyzing productivity problems. He
suggested a manufacturing strategy that included a realign-
ment of priority principles and a commitment to better use
of capacities.
Manufacturing Strategy
A manufacturing system is a competitive weapon for the
firm.7 Manufacturing capabilities such as an adaptive pro-
duction system and low cost production could be considered
as capacity management resources, and driven by capacity
management activities.
Skinner emphasized the importance of the interrela-
tionship between manufacturing operations and corporate
strategies.
Frequently the interrelationship between production operations and corporate strategy is not easily grasped. The notion is simple enough-name Iy, that a company's competitive strategy at a given time places particular demands on its manufacturing function, and, conversely, that the company's manufacturing posture and operations should be specifically designed to fulfill the task demanded by strategic plans. What is more elusive is the set of cause—and—effect factors which determine the linkage between strategy and production operations. Strategy is a set of plans and policies by which a company aims to gain advantages over its competitors.
Problems. 3d ed. (New York: McGraw-Hill Book Company, 1987), 27-28.
Richard B. Chase and Nicholas J. Aquilano, Production and Operations Management; A Life Cycle Approach. 4th ed. (Homewood, 111.: Richard D. Irwin, 1985), 781.
Generally a strategy includes plans for products and the marketing gf these products to a particular set of customers.
Wheelwright suggested the development of a conceptual
framework. His purpose was to determine whether a firm's
manufacturing actions will be truly supportive of corporate
strategy.^
Manufacturing decisions reflect trade-offs among dif-
ferent performance criteria. According to Wheelwright the
following are the four most important performance criteria:
Efficiencv. This criterion encompasses both cost efficiency and capital efficiency and can generally be measured by such factors as return on sales, inventory turnover, and return on assets.
Dependabi1itv. The dependability of a company's products and its delivery and price promises is often exterme1y difficult to measure. Many companies measure it in terms of the "percent of on-time deliveries." Quality. Product quality and reliability, service quality, speed of delivery, and maintenance quality are important aspects of this criterion. For many firms this is easy to measure by internal standards, but as with the other criteria, the key is how the market evaluates quality.
Flexibi1ity. The two major aspects of flexibility changes are in the product and the volume. Special measures are required f^g this criterion, since it is not generally measured.
Capacity management is a term often found in opera-
tions management literature. A generally accepted defini-
0 Wickham Skinner, "Manufacturing—Missing Link in
Corporate Strategy," Harvard Business Review 47 (May-June 1969): 138-39.
g Steven C. Wheelwright, "Reflecting Corporate Strategy
in Manufacturing Decisions," Harvard Business Review 56 (February 1978): 60.
*°Ibid., 61.
tion of capacity management is, however, quite elusive.
Schroeder developed a framework for operations deci-
sions, in which capacity was one of the factors:
Capacity decisions are aimed at providing sufficient output capacity for the organization--not too much and not too little. Capacity decisions include developing capacity plans long-, medium-, and short-term ranges.
Manufacturing effectiveness, though a very important and
broad concept, is not used as a standard term in the litera-
ture. For this study, a manufacturing effectiveness
criteria was developed as a measurable result of short-range
and medium-range capacity management efforts. Long-range
capacity management was excluded from the study because it
belongs mainly outside the domain of production and inven-
tory management. Its main focus is capacity expansion which
is part of econometrics and finance literature. Long-range
capacity management decisions rest with top management,
while this dissertation concentrates on capacity decisions
of middle management. Capacity management is a subsystem in
the production and inventory management system. It inter-
faces with another subsystem known as priority management.
A main core of priority management is the material require-
ments planning (MRP). MRP was originally a computer based
method for managing materials required to carry out a
schedule. MRP has been expanded to become a method of
Roger G. Schroeder, Operations Management: Decision Making in the Operations Function (New York: McGraw-Hill Book Company, 1981), 11-12.
coordinating requirements for materials, capacity, and
possibly other company resources. A fully expanded applica-
tion of the MRP method is called manufacturing resources
planning (MRP1I). 1 2
While MRP II was used in the U.S., the just-in-time
(JIT) philosophy was used in Japan. JIT is a philosophy
that encourages solving problems, not covering them up with
band-aids such as excess inventory, safety stock, or padded
lead times. Zero inventories is the Americanized term for
the JIT. Kanban, the reorder point system used by Toyota,
is one way to achieve the JIT philosophy; MRP II is another
w ay- recent years the JIT philosophy has become popular
in the U . S . 1 3
•
Adopting JIT philosophy constitutes a shift from the
classical "push" type production system to a "pull" type
system. In a push system the driving force is capacity
utilization, requiring capacity to be scheduled first, with
a material feasibility check being secondary. A pull system
is due date driven with customer orders defining due date
requirements. Therefore, the major difference between pull
and push systems lies in the capacity control approach. 1 4
12 Oliver W. Wight, MRP II; Unlocking America's Produc-
tivity Potential (Boston: CBI Publishing, 1984).
13 R. Dave Garwood, "Explaining JIT, MRP II, Kanban,"
PfelM Review and APICS News 4 (October 1984): 66-69.
14 Hans-Martin Schneeberger, "Job Shop Scheduling in
Pull Type Production Environment" (Ph.D. diss., Purdue Uni-versity, 1984).
8
Capacity control and capacity planning are the two elements
that make up capacity management.
Capacity management—planning and control--plays a key
role in developing and implementing a manufacturing strategy
aimed at acheiving effective manufacturing operations.
Existing Approaches to Capacity Management Research
The first step in this study was a search of capacity
management literature. This search revealed studies in two
major areas:
1. Quantitative models for optimizing capacity man-
agement decisions
2. Subjective models promoting the alleged importance
specific capacity management tools and techniques
The work accomplished in each of these areas is
reviewed in the following chapters. The quantitative
approaches are contained in chapter two and the subjective
approaches in chapter three.
Research Objectives
The objective of this study was to examine the
relationship between the intensity of short-range and
medium-range capacity management and the effectiveness of
manufacturing operations. Since there are no universally
accepted measures of these two sets of variables, a
development of factors relating to capacity management and
manufacturing effectiveness was necessary.
Importance of the Study
The process of capacity management is not only theo-
retically interesting but also is of practical importance.
It is a major component of the production and inventory
management system.
In spite of the fact that numerous relevant studies
have been published, no studies were found which attempt to
identify and examine the relationship between the intensity
of capacity management activities and the effectiveness of
manufacturing operations. The absence of this type of
research has prompted the study. In this study, intensity
of capacity management refers to depth, vigor, sophistica-
tion, scope and degree of activities that are concerned with
capacity management.
To a great extent this is the age of naive sophistica-
tion. Many managers choose complex techniques to assist
them in decision making, thinking it is good and free. The
manager should recognize that increased sophistication and
complexity tend to increase cost and decrease understanding
and utility and can be justified only on the basis of
, . 15 resu1ts.
Since capacity management activities represent cost,
and manufacturing effectiveness represents financial
15 Oliver W. Wight, Production and Inventory Manage-
ment in the Computer Aee (Boston: Chaners Books Inter-national Inc., 1974), 85-87.
10
benefits, it is obvious that the relationship between them
is important to a manufacturer. The knowledge of this rela-
tionship will enable the manager to better prioritize the
capacity management activities and determine their intensity
according to their influence on manufacturing effectiveness.
The formulation and testing of a research hypothesis will
facilitate the investigation of the relationship mentioned
above.
Hypothesis
In order to accomplish the research goal, data was
collected to test the null hypothesis:
The intensity of short-range and medium-range
capcity management does not influence manufacturing effec-
tiveness,
0
Definition of Variables
Intensity of short-range and medium—range capacity
management is indicated by the following variables^
1. Production standards—their availability and
sources
2. Priority determination—its criteria, frequency of
use, frequency of change and authority of assignment
3. Delivery dates criteria of determination
4. Material requirements p1anning--its existence and
accuracy
5. Routing information—its availibility and use
ii
6. Capacity utilization—the use of load information
and delivery date determination
7. Backlog measurement--its use in capacity planning
and control
Manufacturing effectiveness is indicated by the fol-
lowing variables:
1- Delivery dates—percentage of the time in which
they are met
2. Lead times—percentage of the time in which they
are shorter than those of competitors
3. Subcontract work--as a percentage of total output
4. Direct labor overtime--as a percentage of total
direct labor
5. Direct labor efficiency—calculated as a ratio
between total standard time and total actual time
Plant and equipment utilization—measured as the
number of weekly shifts of operation
7. Work in process inventory—measured as percentage
of total inventory
Methodo1oev
Research methodology includes the principles and the
procedure utilized to effectively carry out research. Some
of the main steps were discussed in prior sections. The
following is a discusssion of the remainder of the elements
in the methodology for this study.
12
The Data
The data used in this study are of two kinds: primary
and secondary. The primary data were gathered through a
research questionnaire. The secondary data were gathered
through published journal articles, texts, dissertations,
proceedings and reports.
Population and Sample Frame
The population selected to provide data for this study
is the manufacturing firms in the State of Texas with five
hundred or more employees. A11 firms from this group 1isted
in the 1985 Directory of Texas Manufacturers provided the
, 16
sample frame. . The literature and experiences of persons
interviewed indicated that the larger firms provide more
meaningful data.
Questionnaire Development
The questionnaire is contained in Appendix D. The
cover letters are contained in Appendices A,B and C.
Intensity of Short-Range and Medium-Range Capacity Management
An attempt was made to identify the variables, within
the control of management, that are believed to have an
effect on manufacturing effectiveness. The identification
procedure was conducted by means of a search of the litera-
16_ . Directory of Texas Manufacturers (Austin, Texas:
The University of Texas at Austin, 1985).
13
ture, discussion with practitioners and consultation with
academicians.
Intensity of short-range and medium-range capacity
management is indicated by the following variables:
1. Production standards
2. Priority determination
3. Delivery dates determination
4. Material requirements planning
5. Routing information
6. Capacity utilization
7. Backlog measurement
A development of questions came next, followed by the
physical construction of the q u e s t i o n n a i r e . ^ Responses to
questions in sections one through seven of the questionnaire
provided the data used to represent the intensity of
capacity management.
By assigning numerical values to responses to ques-
tions, a measure for each response was developed. An index
was developed for each of these variables. The respondent's
position on that index has been calculated so that every
participating firm received one value for each of the seven
intensity variables. The method of calculating each value
is explained in chapter four.
17 Charles H. Backstrom and Gerald Hursh-Cesar, Survey
Research, 2nd ed. (New York: John Uiley & Sons, 1981).
14
Manufacturing Effectiveness
The methodological process here was very similar to
the one described above. The objective in this area was to
identify variables that validly measure effectiveness and
are available to the researcher.
Manufacturing effectiveness is indicated by the
following variables:
1. Delivery dates performance
2. Lead times
3. Subcontract work
4. Direct labor overtime
5. Direct labor efficiency
6. Plant and equipment utilization
7. Work in process inventory
Responses to questions in section eight of the ques-
tionnaire provided the data used to represent manufacturing
effectiveness. The response values are explained in chapter
four.
Plant Classifications
The questionnaire respondents were classified
according to: (1) number of employees; (2) a two-digit
Standard Industrial Code (SIC); and (3) type of operation
(manufacture to stocky manufacture to ordery and manufacture
to stock and to order). Additional details are contained in
chapter four.
15
Analysis of the Data
Several multivariate data analysis techniques were
utiIized:
1. Factor analysis
2. Canonical correlation analysis
3. Bivariate correlation
4. Multiple linear regression
5. Cross-tabu 1 at i on
6. Analysis of variance
The survey analysis is contained in chapt
chapter includes the techniques, the analysis, and interpre-
tation of the results.
CHAPTER I I
REVIEW OF QUANTITATIVE APPROACHES
Published work in the capacity management field can be
placed in two broad categories. The first category contains
quantitative models for optimizing capacity management
decisions; these are discussed in this chapter. The second
category contains a wide range of subjective approaches that
are not engaged in an optimization process, nor do they seek
to justify the recommendations presented. This category is
discussed in chapter three.
The two basicr management functions relevant in the
case of capacity management are "planning" and "control".
Thus the capacity management literature can be classified as
foilows:
1. Capacity planning (medium-range)
a) Aggregate capacity planning (ACP)
b) Rough-cut capacity planning (RCCP)
c) Capacity requirements planning (CRP)
2. Capacity control (short-range)1
Due to the fundamental difference between planning and
control, most of the published work in the area of capacity
control utilizes the subjective approach, while the capacity
Monks, Operations Management. 460.
16
17
planning literature is primarily quantitative in nature. In
contribution to this dissertation, the quantitative
approaches provided the philosophy of measurable justifica-
tion of results.
Aggregate Capacity Planning
Aggregate capacity planning is concerned with the
determination of production, inventory, and work force
levels, to meet fluctuating demand requirements. Usually,
the physical resources (plant and equipment) of the firm are
assumed to be fixed during the planning horizon. The plan-
ning effort is directed toward the best utilization of those
resources given the demand requirements. A problem usually
rises because the times and quantities imposed by demand
seldomly coincide with the times and quantities that make
for an efficient use of the firm's resources.
Whenever the conditions affecting the production
process are not stable in time due to changes in demand,
cost components or capacity availability, production should
be planned in an aggregate way to obtain effective resource
utilization. Aggregation can take place by consolidating
similar items into product families, different machines into
machine centers, etc. The time horizon of aggregate capac-
planning is dictated by the specific situation; for
example, if demand is seasonal, a full seasonal cycle should
be incorporated into the planning horizon. Commonly, the
18
time frame of aggregate capacity planning which is medium-
range in nature, varies froras six to eighteen months, twelve
months being a suitable figure for most planning systems.2
The costs relevant to aggregate capacity planning can
be categorized as follows:
1. Basic production costs. These are fixed and vari-able costs incurred in producing a given product type in a given time period. Included are direct and indirect labor costs, and regular as wel1 as overtime compensations.
2. Costs associated with changes in the production rate. Typical costs in this category are those involved in hiring, training, and laying off personne1.
3. Inventory holding costs. A mojor component of the inventory holding cost is the cost of capital tied up in inventory. Other components are storing, insurance, taxes, spoilage, and obsolescence.
4. Back 1ogging costs. Usually these costs are very hard to measure and include costs of expediting, loss of customer good will, and loss of sales reve-nues resulting from backlogging.
Aggregate capacity planning models can be classified
according to the assumptions they make about the structure
of the cost components. These models can be classified as:
(1) linear cost models; (2) quadratic cost models; and (3)
general cost models.
Linear Cost Models
Some of the very first models proposed to guide aggre-
2 James B. Dilworth, Production and Operations Manage-
ment: Manufacturing and Nonmanufacturing. 3d ed. (New York-Random House, 1986), 135-66.
3 Arnoldo C. Hax, Handbook of Operations Research:
Foundations and Fundamentals, eds. Joseph J. Moder and Salah E. Elmaghraby (New York: Van Norstad Reinhold Company, 1978), 129.
19
gate capacity planning decisions were linear cost models.
These models considered the work force to be either fixed or
variab1e.
Fixed Work Force Model
With fluctuating sales, a manufacturer must have
fluctuating production, or fluctuating inventory, or both.
Bowman suggested that this problem may be placed into a
transportation method framework. 4 The transportation
method was extended to include multiple time periods. The
problem was one of balancing production overtime costs with
inventory storage costs to result in a minimum total of
these costs. A major advantage of the proposed method was
its calculations simplicity. The main limitation of this
approach was that it did not include hiring or firing costs
or back order costs.
Variable Work Force Models
Hansmann and Hess formulated the aggregate planning
problem in a linear programming format. 5 Constraints such
as maximum amount of overtime could also be used. The
Simplex method was used for solution and sensitivity analy-
4 Edward H. Bowman, "Production Scheduling by the
Transportation Method of Linear Programming," Operations Research 4 (February 1956): 100-103.
5 F. Hansmann, and S. W. Hess, "A Linear Programming
Approach to Production and Employment Scheduling," in Mana-gement Technology, Monograph of the Institute of Management Science, January 1960, 46-52.
20
sis. In cases where the costs were approximately linear
this method produced better results than the early model
known as the HMMS model which used quadratic costs.
O'Malley, Elmaghraby and Jeske developed a production
smoothing system which combined several scheduling tools
into an operational unit. 6 The input to the system was a
forecasted customer demand; the outputs were the required
production levels, size of labor force, planned overtime and
expected inventories of classes and individual end products.
Because of a varying demand, economic manufacturing
quantities were calculated by the method of dynamic program-
ming. The manufacturing progress function was used to
convert units into labor requirements. The operating
schedule was derived by a linear programming formulation
which balanced payroll costs, the costs of labor fluctua-
tions and inventory charges.
Lippman, Rolfe, Wagner and Yuan introduced a model
that minimized the sum of production, employment, and
inventory costs subject to a schedule of known demand
requirements over a finite time horizon. The three decision
variables were: work force producing at regular time, work
force producing on overtime, and the total work force. The
model produced an optimal policy when demands were monotone
0 Richard L. O'Malley, Salah E. Elmaghraby, and John W.
Jeske, Jr., "An Operational System for Smoothing Batch-Type Production," Management Science 12 (June 1966): B433-49.
21
(either increasing or decreasing).^
Yuan proposed a mu1ti-product model. 8 The instrumen-
tal variables in each period were regular time and overtime
production for each product, and total work force. The
objective was to minimize the sum of employment, work force
fluctuation, production, and inventory costs subject to a
schedule of known demand requirements for each product.
Developing optimal production and employment policies, three
types of suboptimal policies were defined as initial hiring,
firing, or leveling of work force.
Von Lanzenauer suggested a model for planning optimal
production and employment levels in mu1tiproduct, multistage
production systems.9 The model determined the amount of
the demand for each product that should be satisfied, be
back 1ogged, or remain unfilled. The results were especially
relevant whenever the production capacity was insufficient
to produce all market demand. The model formulation was
also helpful in certain dynamic market conditions where
backorders and shortages were desirable.
7 , Steven A. Lippman, Alan J. Rolfe, Harvey M. Wagner,
and John S. C. Yuan, "Optimal Production Scheduling and Employment Smoothing with Deterministic Demands," Management Science 14 (November 1967): 127-58.
8 John Shang-Chia Yuan, "Algorithms and Mu1ti-Product
Model in Production Scheduling and Employment Smoothing" (Ph.D. diss., Stanford University, 1968).
9 Christoph Haehling von Lanzenauer, "Production and
Employment Scheduling in Multistage Production Systems," N a v a l—Research Logistics Quarterly 17 (June 1970): 193-98.
22
Lee and Moore showed a technique for the analysis of
problems involving multiple goals and linear relationships.
This technique is known as goal programming. Multiple
goals, such as the following, were specified in this order:
Pi=operate within the limits of productive capacity P2-meet the contracted delivery schedule
P3=operate at a minimum level of 80 percent of regular time capacity
P4=keep inventory to a maximum of three units P5-minimi ze total production and inventory costs P6=ho1d overtime production to a minimum amount. 1 0
This solution provided a satisfaction of these goals
starting with PI and proceeding to the lower priority goals.
This technique utilized tradeoffs between goals of capacity,
delivery schedules, and so on.
' Quadratic Cost Models
Whenever quadratic cost models are used to solve the
aggregate capacity planning problem, the decision rules
generated have a linear structure because the differentia-
tion of a quadratic function produces a linear function.
Thus, the quadratic cost models are also known as linear
decision rules.
The HMMS Model
The aggregate planning problem was first formulated by
Holt, Modi g1iani, and Simon over thirty years a g o . 1 1 This
10_ ,
t> j 4.. ® a n d L * J * M o o r e » "A Practical Approach to
^ 7 4 ! | n | 9 - 9 2 " d U C t l ° n """ ' n V P " t o ^ " • " " . - e n t
1JL harles C. Holt, Franco Modigliani, and Herbert A.
23
formulation resulted in what is called the linear decision
rule (LDR). The LDR model assumed four types of quadratic
costs: (1) regular production costs; (2) hiring and firing
costs; (3) overtime costs; and (4) cost of inventories and
back orders. The objective was to minimize the total cost
by choosing a production level and work force for each
period.
The LDR was applied to a paint factory. It was simple
to use and also had a great deal of intuitive appeal. LDR
has its limitations. It is restricted to the use of quad-
ratic costs, and it reacts to forecast changes gradually,
while in reality changes such as hiring and firing are made
in larger increments. In spite of the limitations and
availability of many models, LDR is still used for compar-
isons.
The LDR was later included in a book with an addi-
tional fourth author. As a result it also became known as
the HMMS model (Holt, Modigliani, Muth and Simon). 1 2
Extension of the HMMS Model
Bergstrom and Smith proposed an extension to the HMMS
model by generalizing the approach to a multiproduct formu-
Simon, "A Linear Decision Rule for Production and Employ-ment Scheduling," Management Science 2 (October 1955): 1-30.
1 2 C* C*. H o I t > F- Modigliani, J. F. Muth, and H. A.
Simon, Planning Production Inventories and Work Force (Englewood Cliffs, New Jersey: Prentice-Hall, 1960).
24
1 ati on and incorporating diminishing marginal revenues in
the objective function.13 To remove the HMMS restriction of
a specified demand, revenue curves were estimated for each
item in each time period. This allowed the determination of
optimal production, sales, inventory and work force levels
so as to maximize profit over a specified time horizon. The
model focused on decision variables in two seperate
functional areas: production and marketing. The HMMS model
on the other hand focused on the production area only.
Peterson offered an extension to the HMMS model to
allow the manufacturer, at a cost, to smooth distribution
orders to achieve less fluctuations in work force, produc-
tion, and inventory levels.14 The smoothing of the distri-
bution was achieved by not requiring the manufacturer to
ship exactly what is ordered. The model provided a means of
balancing the costs and benefits (to the manufacturer) of
smoothing shipments in response to orders and therefore
could be used as an aid in establishing dynamic prices.
Gaalman introduced a method for aggregating multi-item
vers ions of the HMMS „odel. 1 5 The resulting model could be 1 3
G a p y L' Bergstrom and Barnard H. Smith, "Multi-Item Production Planning: An Extension of the HMMS Rules," Man-agement Science 16 (June 1970): B614-29.
n - 1 ! R " d \ P B t r S ° n ' " A n ° P t i m a l Control Model for Smooth-ng Distributor Orders: An Extension of the HMMS Aggregate
Production Work Force Scheduling Theory" (Ph.D. diss., Cornell University, 1969)
G. J. Gaalman, "Optimal Aggregation of Multi-Item
25
considered as a one item production planning model, similar
to the HMMS model. The disaggregation of the optimal deci-
sions derived from the aggregated model lead to optimal
decisions, to the original multi-item model. The proposed
approach revealed that computational savings could be
realized.
Goodman presented a linearization method which was
based upon the method of goal programming. 1 6 The goal pro-
gramming approach was applied to the HMMS quadratic model.
A linear approximation to the original objective function
was made, and computational results were derived. The goal
programming solution was only about three percent higher in
cost than optimal. This indicated that the model provided
an excellent approximation to the quadratic model. The same
approach was applied to higher order cost models and found 0
to be inappropriate.
Chang and Jones proposed a model that dealt with
multiproduct and long production cycle time that included
several production periods. 1 7 As a result, production could
not be started and completed in a given time period. The
Production Smoothing Models," Management science 24 (December 1978): 1733-39.
16_ David A. Goodman, "A Goal Programming Approach to
Aggregate Planning of Production and Work Force," Management Science 20 (August 1974): 1569-75. ~
Robert H. Chang and Charles M. Jones, "Production and Workforce Scheduling Extensions," AIIE Transactions 2 (December 1970) : 326-33. ~~ "
26
product cycle time was defined as the time for one unit of
production to be fabricated, assembled, and delivered to
inventory or the customer. Consideration of the long produc-
tion cycle time was made by integrating a labor set-back
technique into the solution. Labor set-back was defined as
the percentage of total unit labor required during each
production period.
Most aggregate planning models utilized a constant
work force productivity factor; the expected rate of output
capability per employee was kept unchanged over time. Pro-
ductivity rates in many organizations are known to change
with additional manufacturing experience. Ebert extended
the HMMS model to include the productivity factor.^ This
extension resulted in optimal aggregate solutions under
conditions of changing productivity. It could also assist in
product pricing decisions and workforce planning. A major
limitation to the model was the need to estimate learning
curve parameters.
Fisk and Seagle suggested an extension of the HMMS
model that yielded a production rate for each work center in
19
each time period. Each production rate achieved an
optimal balance between inventory costs and costs of chang-
18 Ronald J. Ebert, "Aggregate Planning with Learning
Curve Productivity," Management Science 23 (October 1976): 171-82.
19 John C. Fisk and J. Peter Seagle, "The Integration
of Aggregate Planning with Resource Requirements Planning," Production and Inventory Management 19 (3d Qtr.1978): 81-91.
27
ing capacity. The model integrated aggregate planning with
rough-cut capacity planning. It gave the production planner
a capacity target for each work center and each time bucket.
If planned order releases could fit the targets, cost mini-
mization could have been achieved.
General Cost Models
The linear and quadratic cost models, although appro-
priate for a great number of app1ications, impose several
restrictions on the nature of the cost functions to be used.
Realistic industrial situations tend to exhibit cost func-
tions which are nonlinear and discontinuous and therefore,
cannot be treated by any of the methods outlined
previously. Buffa and Taubert reported the following
factors as mainly responsible for this cost behavior: supply
and demand interactions, manufacturing or purchasing
economies of scale, learning curve effects, quantum jumps in
costs with addition of a new shift, technological and pro-
ductivity changes, and labor slowdown. 2 0
Several aggregate capacity planning methods have been
suggested which attempt to be more responsive to the
complexities introduced by the specific decision environ-
ment. Generally, these more realistic approaches do seek an
optimal solution, but do not guarantee that such will be
20 E. S. Buffa and W. H. Taubert, Production-Inventory
Systems; Planning and Control (Homewood, Illinois: Richard D. Irwin, 1972).
28
found. These methods can be classified according to the
following categories: (1) nonlinear analytical models; (2)
heuristic decision rules; (3) search decision rules; and (4)
simulation.
Nonlinear Analytical Models
These models provide a mathematical treatment of
general nonlinear cost functions. Much of the work in this
area attempted to decompose the multiperiod planning
problem. Linear approximation to a high order cost function
is an option that will enable the use of a linear model.
The range programming linear approximation to a fourth order
cost function, subject to linear constraints, was shown by
21
Laurant. A satisficing range was introduced for each
variable, a range in which all the values of the variable
were considered to entail the same minimal cost.
In order to overcome some of the limitations of early
models Akinc and Roodman introduced a mixed integer program-
ming model for aggregate planning. 2 2 The model was based
on an analytical framework that allowed the user to specify
a set of production options. The model was one that a
production manager should find useful. It made a provision
21 _.,, Gilles Laurant, "A Note on Range Programming: Intro-
^ C I p 8 k S a t ^ C i n g R a n * e ' i n a L.P.," Management 22 (February 1976): 713-16.
22 Umit Akinc and Gary M. Roodman, nA New Approach to
Aggregate Production Planning," I IE Transactions ifi 1986): 88-94.
29
for approximating a wide variety of cost structures. It
could incorporate factors such as union contract provisions
and compulsory maintenance schedules.
In order to facilitate a further discussion of the
analytica1 models additional classification is
needed. These models can be classified into two categories:
convex cost models and concave cost, models*
Convex cost models
Modigliani and Hohn analyzed an aggregate planning
problem for a convex and nondecreasing production cost func-
tion and linear inventory holding cost without production or
23
storage limits. They also assumed that production costs
were unchanged for each period of the total time horizon.
They proposed an algorithm based on fundamental solutions
that can be implemented graphically. The most important
results of Modigliani and Hohn's work are the qualitative
properties associated with planning horizons. They proved
that the total planning interval could be partitioned into
subintervals, defined by planning horizons, within which the
optimal plan was independent of requirements and costs
during other periods. If inventory holding costs were
negligible, a constant rate of production within each
interval was the optimum.
23 F. Modigliani and F. E. Hohn, "Production Planning
Over Time and the Nature of the Expectation and Planning Horizon," Econometrica 23 (January 1955): 46-66.
30
Veinott considered the problem of determining the
optimum production quantities of a single product over a
finite number of time periods so as to minimize convex
production and inventory costs. 2 4 His model did not pena-
lize changes in the production rate. He performed a parame-
tric analysis to study the changes on the optimum production
levels resulting from variations in demand requirements, and
inventory and production bounds. From the results of his
analysis, he developed simple and intuitive computational
procedures for finding optimum production schedules for a
range of parameter values.
Johnson studied a case where no backlogging was
aLlowed, no storage limits were permitted, and inventory
carrying costs were linear. 2 5 The key point of departure
from previous analyses is that he identified each unit of
production with its ultimate destination or period when it
was to be used. Johnson proved a very simple optimum rule:
requirements should be satisfied sequentially in order of
their due dates by the cheapest available means.
Concave cost models
Zangwill showed how to determine minimum cost flows in
24
Arthur F. Veinott, Jr., "Production Planning with Convex Costs: A Parametric Study," Management Science 10 (April 1964): 441-60. ~~
25 S. M. Johnson, "Sequential Production Planning Over
Time at Minimum Cost," Management Science 3 (July 1957)• 435-37.
31
certain types of concave cost networks. 2 6 Although concave
functions can be minimized by an exhaustive search, such an
approach is impractical for all but the simplest of prob-
lems. Zangwill developed theorems which explicitly charac-
terized the extreme points for certain networks. By using
this characterization, algorithms were developed to deter-
mine the minimum concave cost solution. This approach was
applied to a single product production and inventory model,
and a multiple product production and inventory model.
Veinott used a different approach to solve the problem
for multi-facility inventory systems. 2 7 He showed how to
formulate this problem by minimizing a concave function over
the solution set of a Leontief substitution system. The
search of the extreme points to find an optimal solution was
aided by .dynamic programming. The algorithms that were
presented were those whose computational effort increased by
no more than the increase in the size of the problem.
Sobel considered start-up and shut-down costs in his
28
model. These fixed smoothing costs were caused by produc-
26
Wi1 lard I. Zangwill, "Minimum Concave Cost Flows in Certain Networks," Management Science 14 (March 1968): 429-50.
27. .. Arthur F. Veinott, Jr., "Minimum Concave Cost Solu-
tion of Leontief Substitution Models of Mu1ti-Faci1ity Inventory Systems," Operations Research 17 (March-April 1969): 262-91.
28 Matthew J. Sobel, "Smoothing Start-Up and Shut-Down
Costs: Concave Case," Management Science 17 (September 1970): 78-91.
32
ing in a period but not in the one preceeding it, and/or
producing in a period but not in the one following it. Such
costs incurred if, for example, the start-up and the shut-
down decisions caused the transfer of employees from one
activity to another. Inventory, holding costs, and produc-
tion costs were assumed to be concave. The algorithms
developed for optimal policies used some features of the
economic lot size problem.
Heuristic Decision Rules
These rules attempt to bring in the decision maker's
intuition of the problem under consideration, by incorpo-
rating "rules of thumb" that contribute to the solution of
the problem.
Bowman proposed an approach which was quite a
departure from previous thinking. 2 9 He suggested that man-
agement's own past decisions could be incorporated into a
system of improving their present decisions. Decision rules
were developed, with the coefficients in the rules derived
from management's past decisions, rather than from a cost
model. The assumption was that management's decisions were
good, but the use of mathematical decision rules would make
them more consistent. Several cases were presented to test
the theory.
29 E. H. Bowman, "Consistency and Optimality in Manage-
rial Decision Making," Management Science 9 (January 1963)-310-21.
33
Jones developed a heuristic approach to the determina-
tion of two basic parameters: work force and production
30
level. His method was called parametric production plan-
ning. Two rules, one for each parameter, were developed.
The four dimensional universe was searched in order to find
a set of parameters which would result in maximum profit or
minimum cost. In complex and realistic situations the
results of this approach could be superior to results
achieved by HMMS or linear programming.
Masud and Hwang combined a heuristic approach and
analytical decision methods to present a multiple objective
formulation of the multi-product, multi-period aggregate 31
planning problem. In their model, conflicting multiple
objectives were treated explicitly. It provided a more
realistic modeling approach and afforded the production
manager an opportunity to make intelligent trade-off deci-
sions about the different objectives. The fundamental
problem with the traditional single objective approach was
it concealed the issue of conflicting objectives and the
necessity of making informed trade-offs to arrive at an
acceptable solution. 30
Curtis H. Jones, "Parametric Production Planning," Management Science 13 (July 1967): 843-66.
31 Abu S. M. Masud and C. L. Hwang, "An Aggregate
Production Planning Model and Application of Three Multiple Objective Decision Methods," International Journal of Pro-duction Research 18 (November 1980): 741-52.
34
Holt formulated a production decision framework (PDF);
an easy to use algorithm for aggregate planning decision. 3 2
The algorithm was developed for the typical manager who does
not take too seriously the search for optimality, but rather
seeks to find logical decision rules that provide satisfying
short-term solutions. The planning problem was subdivided
into nine mutually exclusive and exhaustive subprob1 ems.
Each subproblem had a predetermined action statement.
Simple calculations were necessary to identify the sub-
problem on hand and the optimal planning horizon so that the
appropriate action could be taken.
Search Decision Rules
These rules consist of the application of hill
climbing techniques to the response surface defined by a
nonlinear cost function and the problem constraints.
Taubert developed a search decision rule (SDR). 3 3
This method could use any cost function. The cost function
was minimized using a pattern search technique. Production
and work force decisions made by the SDR were comparable to
those of the HMMS and total costs were almost identical.
SDR eliminated some of the restrictions imposed by HMMS and
32 Jack A. Holt, "A Heuristic Method for Aggregate
Planning: Production Decision Framework," Journal of 0o*r*-tions Management 2 (October 1981): 41-51. ~ ~
33 William H. Taubert, "The Search Decision Rule
Approach to Operations Planning" (Ph.D. diss., University of California, Los Angeles, 1968).
35
therefore was more realistic. Taubert used his method to
evaluate decision rules with twenty variables and obtained
good results.
Mellichamp and Love utilized a search technique in
their production switching model. 3 4 They argued that the
available mathematical models were seldom used in planning
situations in industry. They observed that managers favored
one large change in work force over a series of smaller and
more frequent changes. As a result, they proposed a modi-
fied random walk production-inventory heuristic that was
simple as well as efficient. It had a thr-ee level produc-
tion and work force rule. Production was switched from one
level to another depending on sales forecast and level of
inventory. Utilizing a search procedure, the production
switching points were determined in a way that minimized any
given cost function. In spite of the simplicity of this
technique it produced schedules which exceeded optimal
schedules by only one to two percent of the total production
cost.
Goodman explored a sectioning search approach as an
alternative method of solving nonlinear aggregate planning
models. After applying the search method to a relatively
large and complex test model, Goodman stated the following
subjective advantages:
34 _ .. . . J o s e P h M- Mel 1ichamp and Robert M. Love, "Production Switching Heuristic for the Aggregate Planning Problem," Management Science 24 (August 1978): 1242-51.
36
1. The method is simple arid can be understood by man-agers as well as technicians.
2. The method is flexible since it does not depend on any particular mathemetica1 structures,
3. Dimensionality offers little problem. In terms of memory, only the cost model and the previous solution need to be stored. Computational require-ments increase only linearly, not exponentially, as the size of the problem grows.
4. The method supplies an integer solution. 5. The method is free of parameters. Hence, simula-
tions or other experiments are not needed in order to obtgjin parameter settings to solve a given mode 1.
Simulation
For a long time simulation has been recognized as an
important modeling tool to deal with situations where analy-
tical models either provide a too simplified representation
of a real world problem or the necessary compuations were
not feasible.
Vergin supplied a classical example of the use of
simulation to select parameters for aggregate planning deci-
36
sxon rules. Using simulation, any cost function or other
objectives could be evaluated. The evaluation of each
decision rule required a seperate simulation run. Any cost
structure was allowed; a departure from the restricted cost
functions used in prior methods.
35 David Allen Goodman, "A Modified Sectioning Search
Approach to Aggregate Planning" (Ph.D. diss., Yale Uni-versity, 1972).
36 R. C. Vergin,"Production Scheduling Under Seasonal
Demand," Journal—of Industrial Engineering 17 (May 1966): 264-66.
37
Cruickshanks, Drescher, and Graves considered a job
shop operation in which all production was for contracted
orders, and no uncommitted finished goods inventory were
37
stocked. A planning window was implemented as a produc-
tion smoothing approach. It required that the planned
production time be reduced or the promised delivery time be
increased or both. A simulation was used to find the best
course of action based on the costs and benefits associated
with each possible choice.
Aggregate capacity planning models were presented and
discussed in this chapter. In order for the review to be
complete, a critical evaluation of these models is
necessary.
Evaluation of Aggregate Capacity Planning Models
Aggregate capacity planning has received substantial
theoretical treatment in the literature for the last thirty
years, widespread implementation of available analytical
techniques, however, has not occured. The HUMS model has
been used as the standard for comparison for new approaches
to aggregate planning. In addition, many extensions to this
model have been published. Yet, it remains an implementa-
tion failure.
37.,, ®* Cruickshanks, Robert D. Drescher, and
Stephen C. Graves, "A Study of Production Smoothing in a Job P Environment," Management Science 30 (March 1984):
368-80.
38
Although the HMMS model was developed in 1955, as
recently as 1978 no company is reported to be using it.
Several possible reasons for implementaion failure of the
HMMS were suggested: (1) its inability to handle integer
variables and/or constraints; (2) the difficulty of con-
structing realistic aggregate cost functions; and (3) a
substantial portion of the cost savings of the HMMS model
could be achieved by improved aggregate inventory management 3 8
a 1 one,
A study done by Shearon shed some light on aggregate
i - 39 planning in industry. The study indicated that production
managers were usually responsible for aggregate planning
decisions, but general managers often reviewed and approved
large changes in inventory or work force. Aggregate deci-
sions were found to be fragmented, with marketing control-
ling variables which influenced demands and operations
controlling supply variables. Most of the participants in
the survey preferred to maintain a level work force whether
the demand was fluctuating, seasonal, or uncertain. In
periods of increasing demand, operations managers added
overtime first, followed by increase in the work force.
38 Leroy B. Schwartz and Robert E. Johnson, "An
Appraisal of the Empirical Performance of the Linear Deci-sion Rule for Aggregate Planning," Management Science 24 (April 1978): 844-49.
39 Winston T. Shearon, Jr., "A Study of the Aggregate
Production Planning Problem" (Ph.D. diss., University of Virginia, 1974). r
39
Meeting schedules was the most important criterion by which
operations managers' job performance was evaluated. It was
followed in order of importance by controlling direct costs,
controlling indirect costs, inventory turnover, and labor
relations.
Lee and Khumawala developed a simulation model of the
aggregate operation of a firm. 4 0 They compared the perform-
ance of four aggregate planning models that were reviewed
above. The models they compared were: C D the HMMS model;
(2) Bowman's management coefficients model; (3) Jones*
parametric production planning model; and (4) Taubert's SDR.
Past data pertaining to actual demand were used so that
comparisons could be made between performance on demand •
forecasts and performance on perfect forecasts. Under per-
fect forecasts, all four methods performed well, with the
search decision rule being slighlty better than the HMMS
model. A more realistic comparison was obtained under
imperfect forecasts. In this case, a wider variation among
the four methods occured. The search decision rule
performed best, followed by the parametric planning model,
the HMMS model, and the management coefficients model.
Quantitative approaches that were reviewed in this
chapter attempt to optimize capacity management decisions.
40 William B. Lee and Basheer M. Khumawala, "Simulation
Testing of Aggregate Production Planning Models in an Imple-mentation Methodology," Management Scienrig 20 (February 1974): 903-11. y
40
The main reason these approaches are not used in industry i>
their complexity. The subjective approaches to capacity
management are presented in chapter three.
CHAPTER I I I
REVIEW OF SUBJECTIVE APPROACHES
The subjective approaches to capacity management were
less scientific than were the quantitative models. Pub-
lished work in this category focused on the promotion of
capacity management tools and techniques, that did not seek
to find an optimum solution to the problem at hand. In
contribution to this dissertation, the subjective approaches
enhanced the development of the following measures: (1) the
intensity of capacity management; and (2) the effectiveness
of manufacturing operations. It also formed a framework for
questionnaire development.
Capacity Planning
Capacity planning techniques can be divided into three
major groups. The three groups are: (1) aggregate capacity
planning (2) rough-cut capacity planning; and (3) capacity
requirements planning.
Aggregate Capacity Planning (ACP)
Aggregate capacity planning determines timing and
quantity for total output of manufacturing processes by
establishing a desirable level for each of the controllable
variables: work force levels, production rates, and
41
42
finished goods inventory levels. Subjective approaches to
aggregate capacity planning are used when the decision maker
is either unaware of mathematical solutions to the problem,
or does not believe that the mathematical models are repre-
sentative enough of the actual situation.
Top management should provide guidance for the aggre-
gate planning activity because the planning decisions.often
reflect basic company policy. Monks outlined some possible
planning policy guidelines!
1. Determine corporate policy regarding controllable variab1es.
2. Use a good forecast as a basis for planning. 3. Plan in appropriate units of capacity.
4. Maintain as stable a work force as is practical. 5. Maintain needed control over inventories. 6. Maintain flexibility to change.
7. Respond to demand in a control led manner. 8. Evaluate planning on a regular basis.
Five subjective approaches to aggregate capacity plan-
ning were identified: (1) nonquantitative haggling; (2)
constant turnover ratio; (3) adjustment of last year's plan;
(4) decision options; and (5) graphing and charting methods.
Nonquantitative Haggling
Silver observed that conflicting objectives are held
by different departments of an organization when it comes to
aggregate capacity planning.^ He also observed that a
Monks, Operations Management. 315.
2 Edward A. Silver, "Medium-Range Aggregate Production
tanning: State of the Art," Production and Inventory Management 13 (1st Qtr. 1972): 15-22.
43
compromise of the conflicting desires was achieved by
bargaining in a noneconomic manner. The policy was usually
dictated by the most persuasive individual rather than being
set in an objective manner.
Constant Turnover Ratio
Another approach commonly used by managers was the
constant turnover ratio. Their performances were often
measured by the turnover ratios they achieved. Turnover
ratio could be defined as total sales divided by average
inventory. As a result it became appealing to set produc-
tion rates so as to achieve a constant desirable tunover
ratio, despite the fact that this was not the most econom-
3 ical choice.
Adjustment of Last Year's P l a n
The weakness of this approach was similar to that of
the constant turnover ratio. Silver identified another
common approach often used in industry.4 In this approach a
previous plan was slightly adjusted so as to meet current
conditions. The implicit assumption that the previous plan
was optimal or close to optimal could get management locked
into a series of poor plans.
Decision Options
3Ibid.
4Ibid., 23.
44
The decision options available in aggregate capacity
planning can be divided into two types: (1) those modifying
demand; and (2) those modifying supply. The modification of
demand is considered as outside the domain of the opera-
tional focus and inside that of marketing, finance, and
administration, and therefore will not be discussed here.
Modification of the supply can be achieved through:
1. Changing work force size which: a) increases hiring and training costs; b) results in lower productivity of new employees; c) increases costs associated with terminating
workers; and
d) increases the risk of losing skilled workers during periods of decreased demand.
2. Changing inventory level which:
a) may cause excessive inventory holding costs during periods of inventory buildup; and
b) may cause back-order or" lost-sales costs when peak demand exceeds the capacity of the system to build up inventory.
3. Changing production rate through:
a) overtime, which increases per-hour labor rates and probably decreases labor efficiency;
b) underuti1ization of labor, which either in-creases per-unit labor cost (if ail workers are paid for a standard number of hours and for lower output) or results in worker dissatisfac-tion (when work hours are reduced below the standard number workers have come to expect)-
c) subcontracting, which often increases per-unit cost and may increase quality-control costs; and
d) adding additional shifts, which is a commitment o a permanent change in production require-
ments. 4. Making simple adjustments to physical facilities
such as warehousing and storage space.
Additional decision options that were suggested
5 j .. W 1 1 ' i ^ m J* S a w a y a » J r- a n d William C. Giauque, Pro-
n a " d Operations Management (New York: Harcourt iT^Te Jovanovich, 1986), 239. Brace
45
include: the use of alternate routings, additional tooling,
changing make/buy decisions, and the reallocation of the
work force to different jobs. 6 Most of the decision options
listed above are applicable to capacity control.
The use of any single decision option mentioned above
constitutes a pure strategy. The use of two or more of the
decision options constitutes a mixed strategy. Varying only
the inventory level or varying only the work force are
examples of a pure strategy. Varying work force and inven-
tory levels is an example of a mixed strategy. Strategies"
can be combined in an infinite number of ways to arrive at
an operating plan that managers feel is feasible and
desirable. The use of the decision options approach can be
aided by the use of graphic and charting methods.
Graphic and Charting Methods
The graphic and charting techniques basically work
with a few variables at a time on a triai-and-error basis.
Charts are used in the development of the cost of each of
the strategies that are considered. Cost minimization is
the criterion for strategy selection. Since a limited
number of strategies are considered, an optimal solution
usually cannot be achieved. The use of histograms and
6 Roger Ahrens, "Capacity Management: Who is Account-
able?," in Proceedings of the 25th Annual International Conference of the American Production and Inventory Cont.rnl Society. October. qofi-Ann —
46
cumulative graphs of forecasts can also aid the decisi
making process.
on 7
Rough-Cut Capacity Planning (RCCP)
Rough-cut capacity planning is also known as resource
requirements planning (RRP). it is an approach to obtain a
rough-cut analysis of the impact that a master production
schedule (MPS) will have on the capacity of a company. It
can be used to sum and evaluate the work load that the MPS
imposes either on all work centers or on only selected work
centers where resources are limited, expensive, or difficult
to obtain.
Campbell summarized the fundamentals of RCCP:
1. Determine the capacity of the resources (work centers) involved.
2. Determine the load by the time period, represented by the products and quantities in the master schedu1e.
3. Compare the capacity and load, time period by time period, noticing any significant differences.
4. Report the differences.
Clark presented this type of planning as one which can
utilize a variety of techniques, such as load profile simu-
lations, and bills of labor.9 Rough-cut capacity planning
Di1worth, Productions and Operations, 145-51.
0 Kenneth L. Campbell, "Rough-Cut Capacity Planning:
What it is and How to Use it," in Proceedings of thg nternationa 1—APICS Conference. October, 1982, 406-9.
I " C l a f k ' "Capacity Management," in Proceeding* 2 2 d International APICS Conference. October. 1979.
iyi yb•
47
techniques utilize MPS information, but do not utilize de-
tailed low level information produced by the material
requirements planning system (MRP).
The rough-cut capacity planning techniques were: (1)
capacity planning using overall factors; (2) capacity bills;
(3) resource profiles; (4) bill of resource; (5) family bill
of labor; (6) load profiles; and (7) capacity planning
performance factor.
Capacity Planning Usinp> Overall Factors (CPOF)
Berry, Schmitt, and Vollmann offered-the CPOF
technique:
The CPOF technique is based upon planning factors involving direct labor standards for end products in the
S. When these planning factors are applied to the MPS data, overall manpower capacity requirements are esti-
-,1 T ^ S ° V e r a I 1 e s 1 i m ate is frequently allocated to individual work centers on the basis of historical data on shop work loads. CPOF plans are usually stated in terms of weekly or monthly time periods, and are period-cally revised as the firm makes changes to the MPS.
The CPOF technique, or variants of it, are found in a number of manufacturing firms. The data requirements are minimal, involving principal accounting system data
h°I- f ° r m a i i 0 n S U C h a S P r o d u c t routing files and detailed time standards. As a consequence, CPOF plans produce only approximations of the actual time-phased
capacity requirements at individual work c e n t e r s . 0
The CPOF technique resulted in a capacity plan. The
plan was based upon the same historical ratio of load in the
v«.. 1 0 W i I i i a m V" B e r r y » Thomas J. Schmitt, and Thomas E.
mann, apacity Planning Techniques for Manufacturing Control Systems: Information Requirements and Operational
° f O p e r a t i o n s t 1 a n a i' p m p" t 3 (November
48
work center for each time period.
Capacity Bills (CB)
Osgood introduced the capacity bills technique which
provided a much more direct linkage between individual end
products in the MPS and the capacity required at individual
work centers than did the CPOF.11 This technique required
more data. Routing, operation time standards, and bills of
material were utilized to develop a capacity plan using the
capacity bills technique. The bill of capacity indicated the
total standard time per unit required to produce an end
product in each work center used in its manufacturing.
After the bill of capacity for each end product was pre-
pared, the MPS could be used to estimate the total require-
ments at each of the work centers. The capacity plan that
was developed reflected the actual period to period
differences in product mix.
Resource Profiles (RP)
This technique provided a time-phasing dimension not
available in the CPOF and CB techniques. In the resource
profiles technique, production lead time data were added to
the capacity bills data base in order to provide a time-
phased profile of resource usage by end product, by work
center, and by period. The profile was used to generate the
n - n I1,"1'113111 R" 0s8°°d, "How to Plan Capacity Using The To !JL Labor," m Proceedings of the 19th International Ar* ICS Conference. October. 197fi. 281-88.
49
capacity plan. The technique accommodated both product mix
variations and operation lead times as part of the prepera-
12 tion of capacity plans.
Bill of Resource
Bechler suggested the use of a bill of resource that
was similar to RP technique though the structure used was
13
different- The product groups that were covered by the
MPS were defined using a bi11 of resource. The products
were structured in a bill of material format but using
resource requirements instead of part requirements. The
resources could represent any measure of capacity desired.
Some examples were: man hours, machine hours, test fixtures,
floor space, and electricity. As a result time-phased
resource requirements plans were developed for all resources
that were included in the bill.
Family Bill of Labor
Erhorn emphasized the use of the family bill of labor
in situations where only the labor resource was considered.
In companies producing a large number of end items, family
summarization was the only efficient way to achieve rough-
12 W. L. Berry, T. G. Schmitt, and T. E. Vollmann, ">
Tutorial on Different Procedures for Planning Work Center Capacity Levels," Indiana University Discussion Paper 155 (September 1980): 1-8.
13 Robert E. Bechler, "Resoource Requirements Plan-
ning," in Proceedings of the 23d International APICS Conference. October. 1980. 332-34.
50
cut capacity planning. The process used for classification
of product families was described in the following steps:
1. First, classify all end items into broad categories, based on similarities of application.
2. Further classify within each application category, those end items with similar or common components. Note: similar in this case means components that are essentially of identical design, but which may differ in terms of size or finish.
3. Do not consider purchased components in the classi-fication process, since these have no effect on your capacity requirements.
4. Finally, establish families by further classifying your groupings from step 2. This is accomplished using the additional criteria of similarity of manu-facturing process. Each family will contain end items whose components look the^ame, and are produced on the same machinery.
Load Prof i1es
Clark advocated the use of load profiles as a planning
tool. 1 5 This technique was similar to the RP technique but
did not provide end product information. A load profile was
prepared for each of the work centers for which requirements
were indicated. The load profile showed weekly work loads
and normal available capacity. If a load profile was unac-
ceptable, a revision of the MPS was executed. The revision
process could be repeated more than one time until a desir-
able production plan was found, one that appeared to be the
best way to achieve a match between resources and demand for
14 Craig R. Erhorn, "Developing and Using Rough-Cut
Capacity Planning," in Proceedings of the 26th International APICS Conference. November. 1983. 238-41.
1 5James T. Clark, "Capacity Management,: Part Two," in Proceedings of the 23rd International APICS Conference. October. 1980. 335-41.
5 1
resources. If by using this procedure the load profile
could not be leveled within the current capacity level, the
problem had to be brought to management's attention for a
selection of corrective action(s).
Capacity Planning Performance Factor (CPPF)
Lunz argued that a fundamental factor was not commonly
considered while performing calculations of capacity re-
quirements and available capacity in conjunction with
techniques such as those that were presented a b o v e . ^
Consideration of this factor, he stated, was necessary in
order to successfully execute the capacity planning process.
The CPPF had to be utilizedin order to determine how many
standard hours per day had to be used for each direct labor
person, or for each machine. Factors such as allowable rest
periods, machine break downs, efficiency percentage, rework,
etc. reduced the available hours and did not contribute to
the accomplishment of direct labor standards. These factors
were used to calculate the appropriate CPPF.
Strengths and Weaknesses
Ahrens listed the following strengths and weaknesses
of rough-cut capacity planning.
The strengths were:
16 Alfred G. Lunz, wThe Missing Factors: The Real Keys
to Effective Capacity Requirements Planning and Control,w
Production and Inventory Management 22 (2d Qtr. 1981): i-12.
52
It does not require a computer although the process is enhanced if assisted by a computer.
Routings are not essential for every item.
J t s l m P , e r - 0 n l y key or critical work centers are considered.
Quick simulation of capacity requirements prior to MRP is provided.
Rescheduling the MPS for capacity over/under loads is made easier. When using more detailed methods of deter-mining capacity requirements the relationship between the capacity required and the MPS item is not clear.
l t P r o d u c t i o n Planning in allocating capacity to product families by providing quick answers to "what if" questions.
The weaknesses were:
It is not precise.
Component and work-in-process inventory are ignored.
RCCP only considers critical work centers. It assumes the non critical work center capacities can be manipu-lated as required.
Lead time offsets are not considered.
It does not track performance to plan.* 7
Evaluation Criteria
Njus examined the effectiveness of a RCCP model after
its implementation. 1 8 Credibility and turnaround time were
the major considerations in the evaluation. The accuracy of
r * | 7R°ger Ahrens, "Basics of Capacity Planning and Control, in Proceedings of the 24th International apitq Conference. October. 1 9 f l T T 2 3 2 - 3 5 . ~ ' ~
18 John Njus, "Resource Requirements Planning: The
M odeI," in Proceedings of the 26th International Ai-Mib Conference. November. 1983. 480-83. ~ ~
53
the RCCP model was established by comparing its results with
an existing standard for planning. The existing standard
for planning was the gross current work standard direct
labor load report. This report was calculated by exploding
the detail part requirements for a given MPS. The turn-
around time for the RCCP report was compared to that for the
existing gross labor report.
Capacity Requirements Planning (CRP)
Plossl and Wight proposed the term "capacity require-
ments planning" to replace what was previously called
"infinite loading" or "loading to infinite capacity." 1 9 CRP
utilized the low-level detailed MRP information. It
actually went beyond infinite loading, however, for it in-
cluded planned orders as well as released orders and
involved an iterative plan-replan process. Replanning con-
tinued until a realistic load was developed.
C A P A C j n HEQUIHEHEHTS PLANNING (CRP)—The function of establishing, measuring, and adjusting limits or levels
+ k • ° a P a C + yl t e r ™ capacity requirements planning in this context is the process of deter.ining ho» „uch
Iht l a C m ; t c h l T , g resources are required to accomplish the tasks of production. Open shop orders, and planned or ers in the MRP system, are input to CRP which "trans-
t i m b e r i o d * 2 ® 1 ^ 6 " i n t ° h ° U r S ° f W ° r k b y w o r k c e n t " by
19 _ George W. Plossl and Oliver W. Wight, "Capacity
r i a " 3 d " g t r i 9 ? 3 n ° 3 ; : 6 ^ ° d u c t l ° n
20 re i. F" W a I , a c e ' APICS Dictionary. 5th ed.
alls Church, Virginia: American Production and Inventory Control Society, 1984), 4. inventory
54
Load int>
Loading refers to the assigning of work load to a work
center. There are two types of loading methods. The first
is called infinite loading and the other is called finite
1oading.
Infinite loading
The capacity requirements planning (CRP) technique
that was discussed above is classified as an infinite
loading technique.
in Fth^ Tf- L 0 A D I N^~^ S h O W i n g t h G W ° r k b e h i n d work centers the time periods required regardless of the capacity
Vol* 'V " " ' O ™ t M S -or*. The ter„ i . t U t f ^
loading is considered to be obsolete today, although the pecific computer programs used to do infinite loading
can now be used to perform the technique called capacity requirements planning. Infinite loading was a grosl misnomer to start with, implying that a'load could be no.f % 5 a C t ° r y r eg a rdle ss of its availability to perform. The poor terminology obscured the fact that it is necessary to generate capacity requirements and co.pare these with available capacity befo , . t o
adjust requirements to capacity.21
Finite loading
The second type of loading is finite loading.
I o r e T L r k A ? i t r i C f n C f P t U a ^ y ^ " e a n s P""ing no •ore work into a factory than the factory can be expected to execute. The specific term usual 1y refers to a conputer technique that involves automatic shop
operation!"^^^Si0n ° r d " t 0 ' °*d ° P - a t i o ^ y
F i n i t e l o a d i"g does not usually work well at the CRP
Ibid., 14. 22
Ibid., i1.
55
stage because it forces changes back onto the master produc-
tion schedule that are not always the best solutions to the
scheduling problem. Finite loading is a useful technique
for single work centers in the priority control stage where
jobs are being scheduled.
The information manual for CAPOSS-E an IBM finite and
infinite loading system provides a list of the benefits of
capaci ty management:
Adherence to scheduled due dates. Reduction of delivery time. Increased customer confidence.
More efficient machine loading, which releases addi-tional capacity.
Easier control of schedules.
Recognition of overloads in time to take action. 2 3
The CRP Process
End item requirements arising from the aggregate plan
and MPS are exploded into tentative planned orders for
components by the MRP system. The CRP system then converts
these orders into standard labor and machine hours of load
on the appropriate workers and/or on the machines as iden-
tified from the work center status and shop routing files.
The output is a load projection report by work center. If
work center capacities are adequate, the planned order
releases are verified for the MRP system, and released
orders become purchase and shop orders. Workload reports
23 International Business Machines, Capacity Planning
and Operation Sequencing System—Extended: General Informa-tion Manual, GH12-5119-0, (White Plains, New York., 1977) 13-14. '
56
some are also made for use in input/output control. If
initial load projection reports reveal inadequate capacity,
either the capacity must be modified or the master schedule
24 revised.
In the process described above, the master production
schedule drives an MRP system, which passes planned orders
to CRP. Wright suggested an alternative to this approach. 2 5
In his proposal the master production schedule directly
drove the CRP while in the classical approach CRP was driven
by the MRP.
K a m i developed a systematic methodology to character-
ize and analyze the flow of work through a work station and
related this flow to the nominal capacity of the station. 2 6
Operation of the station was measured by work-in-process,
delay, and underload. Flow between stations was measured by
queue length and lead times. Performance was evaluated by
the degree of underload and overload planned for the sta-
tion, and the degree to which MRP imposed lead times could
be achieved. To complete the discussion of the CRP, its
strengths and weaknesses wi11 be presented.
24 5 a y
l iP. I O Sf 1 a n d T o m M o o r e ' "Job-Shop Scheduling: A
Confer n 1 ! P r o c e e d i n « s of the 25th International APIrg Conference. October. 1982. 97-104.
25
Svstem Bm " r i ? h * ' " H o w t o U s e a Detailed Scheduling national APirS " a t ® r i a 1 s ' " l n Proceedings of the 25th lnfPr-nationa I—APICS Conference. October. 1982. 85-86.
26n
S v . m . . R e " y e n Karni, "Capacity Requirements Planning: A y ematization, International Journal of Production
Research 20 (November 1982): 715-39.
57
Strengths and Weaknesses
Behling provided a detailed list of CRP strengths and
weaknesses.
The strengths were:
Net capacity required is accurately depicted since on-hand and work-in-process inventories are considered in determining the requirements plan, and completed opera-tions are considered in determining the hours required.
Capacity requirements are developed for all work centers on resources which are defined by the routing informa-t iori.
Time-phased visibility of bottlenecks and unbalanced loads is provided for the horizon represented by the production plan or master schedule less the lead time offset.
The weaknesses were:
Data requirements are extensive since accurate informa-tion is required at a minimum for routings, order status, and operation status.
Extensive computer assistance is required due to the voluminous number of records processed and calculations performed.
Visibility for corrective action is difficult because the pegging of capacity requirements to specific master schedules is limited.
Predefined scheduling rules don't always represent actual shop operation, thus limiting the accuracy of the time phasing in the net capacity required.
Input/Output Planning
Belt proposed a technique called input/output (I/O)
planning as a replacement for capacity requirements planning
27 Richard L. Behling, "Supply Chain Management with
Capacity Constraints," in Proceedings of the 25th Interna-tional APICS Conference. October. 1982. 379-83.
58
(CRP). The proposal constituted an integration of
capacity planning and capacity control. While CRP is a load
vs. capacity method the input/output planning method
utilizes a different approach which is similar to the one
used by the capacity control technique called input/output
control. Belt pointed out that load and capacity cannot be
directly compared. In the CRP, it is. invalid to match up
load which is measured in hours, to capacity which is a
rate expressed in units per hour.
In the proposed input/output planning method, planned
input is used instead of load, and planned output is used
instead of capacity. This terminological transformation
iminates the invalid comparison mentioned above. The
input/output plan shows the planned input, planned output,
Planned queue, and planned queue in weeks of putput all on a
weekly basis. The proposed format is concise and under-
standable. Action recommended by input/output planning is
based upon a comparison of planned queue in weeks of output
and planned lead time. Employing the input/output tech-
niques for both capacity planning and capacity control means
that a single report format can serve both functions.
The input/output planning technique is superior to
machine loading (utilized by CRP) for the following reasons:
23 Control Integrating Capacity Planning and 1976): 0 2 ^ ° d u c t l c m a n f i Inventory Hanagpmpnf i 7 ( l s t Q t r -
59
1.
6.
7.
It focuses on stabilizing the planned queue or backlog as the primary capacity planning objective, thus recognizing the true role of backlog in the shop. Backlog is stabilized to a preplanned level equivalent to planned lead time by adding capacity, reducing input, or some combination of the two, and true capacity needs are defined easily as a result. Machine loading tries only to match input ("load")' with output, and ignores queue fluctuations.
2. I/O planning validates the lead time used in inven-tory planning, by seeking to stabilize queues around the inventory-control system's planned lead time value. Machine loading does not try to do this.
3. I/O planning recognizes that backlogs will always vary somewhat and seeks stability within a certain tolerable range of variation. Machine loading, in trying to equate input with output, attempts to keep the backlog size rigidly fixed and not permit it to fulfill its proper function of a physical and psy-chological buffer.
4. I/O planning offers more flexible alternatives to the capacity planner by giving him visibility as to future input, future output, and future queue varia-tions by time period. Capacity planning becomes more precise and more realistic than the numbers-matching approach of machine loading.
5. I/O planning is useful for intermediate as well as starting work centers since it clearly shows the evolution of backlog time period by time period, based on the scheduled input rate from MRP. Directly modifying the input rate to intermediate work centers remains a difficult proposition. But seeing the peaks and valleys of input and queues, rather than an average input for all time periods, helps the planner to decide when to change the planned output rate. Machine loading offers only the possibility of equating "load" with capacity for both intermediate and starting work centers.
Changes to planned lead times are easier to imple-ment with I/O planning, which will show the results clearly, in terms of queue variations, by time period. Machine loading has no provision for showing this.
An integrated I/O format may be used for both capac-ity planning and control functions in production control systems, both tailor-made as well as standard packages, rather than having machine load reportfjgfor the one and input/output reports for the other.
29 Ibid., 23-24.
60
In order to further facilitate the understanding of
capacity planning methods, some comparisons and evaluations
will be presented.
Capacity Requirements Planning (CRP) Rough-Cut Capacity Planning (RCCP).
Sari provided a comparison between CRP and RCCP using
manufacturing and product charac-teristics similar to those
utilized by Everdell in the development of a MPS. 3 0 Review
of the respective strengths and weaknesses of CRP and RCCP
revealed that the two tools very much complemented each
other in many respects. In addition certain characteristics
of the manufacturing environment or product tend to favor
one tool or the other.
The following were some of Sari's considerations:
1. Type of manufacturer and facility. Flow-like
manufacturers frequently rely exclusively on RCCP. Very
little beyond loading to process capacity is needed. Dis-
crete manufacturers, particularly those with common use
equipment and facilities, do not rely exclusively on RCCP.
The load profiles of RCCP assume a manufacturing flow that
does not depict well the effects of lead time variability.
30 r -4. FA J ° h n S a r i » "Resource Requirements Planning and Capacity Requirements Planning: The Case for Each and Both »
H i r ° r " ? * " i ' ? " , h - ' Biiio A I V ' . f 1' a n d R o ® e y " Everdell, "Planning ills of Materials: Tools for Master Scheduling," in Pro-
ceedings of the 26th Internatinn* 1 a p t C S C n n f L J November. ?r-;.cb
61
Even though CRP suffers from the same problem it does
provide additional visibility into the situation.
2. Lower level independent demand. Manufacturers with
significant spare part business, interplant component
supply situations, etc., may utilize CRP to reflect this
lower demand.
Performance Comparison nf Four Capacity Planning Techniques
Schmitt, Berry, and Vollmann used a simulation model
of a two stage fabrication/assembly process to compare the
performance of four capacity planning procedures. The proce-
dures were aimed at developing work center capacity plans
designed to ensure the production of components and assem-
blies as specified by MRP. Three of the procedures examined
were rough-cut capacity planning procedures. The procedures
in this group were: capacity planning using overall factors
(CPOF), capacity bills (CB), and resource profiles (RP).
The fourth procedure was the capacity requirements planning
(CRP). The conclusions of the comparison were:
T h e results indicate that the performance of a pro-cedure when measured against the MPS depends on the operating conditions of the manufacturing system Th*> results also indicate that the choice plrtiauZr
° f * e " r eP resents a compromise among the benefits of improved MPS performance, the costs of preparing and processing data, and the premium expenses - p a c i f y f e v e T s ^ l ' r 0 q U e n t ^ u s t m e n t s in work center
Vollman l T^An aAn?' f 0 1" 1*"' W iJli*m L. Berry, and Thomas E. > lysis of Capacity Planning Procedures for a
62
A control step always follows the planning step. This
statement is true in regard to the capacity function. After
the completion of capacity planning, the stage is set for
capacity control.
Capacity Contrnl
APICS Dictionary defines capacity control as:
CAPACITY CONTROL--The process of measuring production
* comparing it with the capacity requirements p an determining if the variance exceeds preestab 1ished limits and taking corrggtive action to get back on plan if limits are exceeded.
Capacity control complements priority control. Pri-
ority control activities include order release, dispatching,
and status control, while capacity control activities
include lead time control and input/output control. 3 3
Lead Time Control
An effective lead time control can be an important
step towards meeting the production and inventory control
objectives of customer service, minimum inventory investment
and planned operating efficiency.
Belt introduced a modern concept of lead time
? S t ? n 1 ? 1 K R e q l ' o £ f ? 0 n t a P l a n n i n S System," Decisions S c i e n c e 15 (October 1984): 522-41.
32 Wallace, APICS Dictionary. 4.
33 G. W. Plossl, "Tactics for Manufacturing Control "
Production and—Inventory Management 15 (3d Qtr. 1974)-21-34.
63
control. 3 4 Traditionally, lead time was thought as given
and uncontrollable. The new concept suggested that lead
time is a controllable resource and should be managed like
any other resource in order to maximize return on invest-
ment. Lead time should be allocated sparingly. It should be
balanced with other productive resources such as man/machine
resources. Lack of balance will make it impossible for the
shop to run smoothly. Lead time should also be controlled
so that actual lead times are approaching the planned lead
times using input/output control. Before discussing the
principles of lead time control the term must be defined.
Lead Time Definition
Lankford presented a detailed anatomy of lead time. 3 5
As defined for production control, lead time is the elapsed
time between the release of an order for manufacturing and
the receipt of that order into stores. This is the defini-
tion of manufacturing lead time CMLT), the time required for
production or processing activities. It does not include
pre-manufacturing activities such as engineering, design and
material purchasing. Each manufactured item in the bill of
materials has its individual MLT and each purchased item has
its procurement lead time.
34 Bill Belt, "The New ABC's of Lead-Time Management "
Production and Inventory Management 15 (3d Qtr.i974) : 81-91.
35 t u , . n , r
R " L:, L a^ k? o r<*, "Short-Term Planning of Manufac-
APirS r J a y ' o n O C e e C * * n g S Of the Plst I n t p m a t i nna 1 AH1CS Conference. October. 1 9 7 8 ^ 3 7 - 3 9 . ~
64
When quoting a delivery date to customers total lead
time must be used. Total lead time includes pre-
manufacturing activities, MLT, and post-manufacturing acti-
vities such as crating or waiting for shipment.
Manufacturing lead time consists of operation times
and inter-operation times. Operation time consists of set-
up and run time. Inter-operation time consists of queue
time and transit time. Queue time is the time a job spends
in a backlog waiting for another job to be finished.
Transit time includes wait time and move time. Wait time is
the time a job spends waiting to be moved, while move time
is the actual traveling time of the job. The dominant
element of MLT is queue time, which is estimated to account
for seventy to ninety percent of the total. Studies
suggested that ten percent or less of the MLT in an average
company is actual run time. 3 6
Lead Time Variability
Heard focused on the importance of the variability in
37
lead times. He observed that the significance of lead
time variability was not as evident as that of lead time
length. Manufacturing control systems were notoriously one 36
on i-.J ~ - 1 V e » D* " i g h t ' nInput/Ouput Control. A Real Handle
s". n a n d t n v e n t ° r v i i <3d
37 o J i..Ed H e a r d ' a n d George Plossl, "Lead Time Revisited " Production and Inventory Management 25 (3d Qtr. 1984): 3 3 A 7 •
65
sided with respect to completion date. Early completion of
orders were neither appreciated nor understood, though they
caused an unnecessary increase in finished goods inventory.
Materials and capacity devoted to completing unneeded orders
early could not be used to complete needed orders on time.
Wight described five situations providing evidence of
poor lead time control. 3 8 The situations were: (1)
excessive inventories of parts and finished material com-
bined with poor customer service; (2) an inability to make
realistic delivery promises and meet them; (3) excessive
expediting; (4) a chronic lack of space in the plant; and
(5) plants that are always behind schedule. The root of the
problem was large backlogs caused by a surge in lead time,
erratic plant input, and inability to plan and control
output rates.
Moghaddam and Bimmerle identified nineteen factors
influencing manufacturing lead time. 3 9 They ranked those
factors according to the importance placed on them by the
manufacturers. The ten most important factors in descend-
ing order were: (1) commitment to customer on shipping
date; (2) ability to plan and control capacity; (3) the
number of resource constraints; (4) shop utilization (load);
38 Wight, " Input/Output Control," 9-30.
39 . John M. Moghaddam, and Charles F. Bimmerle,
"Managing Manufacturing Lead Time: A Research Report," in Proceedings of the 24th International AP1CS Confprpnnp. October. 1981. 163-64^
66
b'llty to plan and control Inventory level; (6) the
variety of products; <7, priority ru.es; (8» ,. b o r f l e I i _
b " " , ! < 9 > t h e d * « ' ~ ° f »"y "or*; and U0> engineer-ing order change.
Control Techniques
Lead time variability is influenced by the contro,
technique used. Moghaddam and Bimmerle determined that the
techniques used by manufacturers to reduce MLT were not of
equal importance.40 The ten most important techniques in
cending order were: (l) increase the output rate by
extra manning; <2> increase- shop floor control; (3) reduc-
rework and scrap; (4) increase the output rate by
overtime; (5) replan production output level; (6) combine
the planning and control of capacity with the planning and
control of miv- (~7\
«i*. (7) plan capacity requirements in the
latest possible groups of items, <e> increase input.output
control; < 9 ) increase expediting ,s«ook chasing; and <iO, removing work for subcontracting.
voung introduced a cost based control technique.41 He
presented an overview of the
the costs associated with manufac-
turing lead time. Aithough many of the costs were difficult
to document or even unmeasurab!e, they existed. P u U i n g 40
Ibid., 164-65.
Proceed ?; ^ h e n | i d " y n ? e r S t ? n d l n g S h ° p L s a d T l » « , October. fq7a. ffe -3 " " " C o n f e r s .
n in
67
together enough of the costs formed a management judgement
on the extension or contraction of lead times. After
changes in lead times were implemented, the formation of the
management judgement was repeated in order to evaluate the
change.
Input/Output Control
Wight introduced input/output control as a technique
aimed at reducing and controlling lead time. The reduc-
tion and control of backlogs, and thus lead times, can be
achieved by following one simple rule: the input to a shop
must be equal or less than the output. In spite of the
clarity of this rule, more times than not, the exact
opposite occurs. The input/output control technique facili-
tates control in three main ways: (i> projecting capacity
requirements into the future; (2) showing planned input and
output at the level rate; and (3) showing the relationship
between input and output.
In the input/output control report, a production rate
has been planned and then leveled out. This level rate is
projected into the future so that a plant foreman would have
enough time to make any necessary adjustments to capacity.
The report shows the planned input, actual input, planned
output, actual output, and cumulative deviations all on a
weekly basis. The integration of capacity planning and con-
42 Wight, "Input/Output Control," 9-30.
68
trol using input/output planning and control was discussed
in the I/O planning section.
Overview
The literature review that was presented in chapters
two and three identified a research topic and contributed to
the research design.
A review of quantitative models in chapter two identi-
figd a very- low degree of implementation due to complexity
and difficulty in developing input data. It indicated a
need for improvement. The quantitative models provided the
fundamental concept that a measurement of results is neces-
sary in order to justify recommendations.
A review of the subjective models identified their
basic limitations. These models do not provide an optimal
solution, nor do they attempt to justify their recommenda-
tions. These models, however, contributed to development of
intensity and effectiveness measures and the questionnaire.
These topics are presented in chapter four.
CHAPTER IV
DATA COLLECTION SURVEY
The selection of the population and sample frame for
this study was described in chapter one. The completed
mailing list included 296 manufacturing plants in the State
of Texas.
Design of Questionnaire
Selection of variables, development of questions and
the assignment of numerical values to potential responses
were the next steps performed. The final step in the design
of the questionnaire was its physical construction.
Selection of Variables
Both the intensity variables and the effectiveness
variables were selected by means of a literature review,
consultation with academicians and practitioners, and
personal experience. Detailed lists and explanations of the
two variable groups appeared in chapter one. These lists
represent a reduction of original lists. During a pilot
study and consultation with practitioners, it became evident
that the number of variables, and subsequently the number of
questions had to be reduced. Some of the main reasons were.
(1) not all desirable information was readily available to
69
70
potential participants; (2) a lengthy, time consuming ques-
tionnaire would discourage participation; and (3) the confi-
dential nature of part of the information would result in
incomplete questionnaires.
Development of Questions
For the effectiveness measures, one question per vari-
able was developed. However, for the intensity measures
several questions per variable were necessary. A list of
the variables (intensity and effectiveness) and their corre-
sponding questions are shown in appendix E. The survey
questionnaire is contained in appendix D.
Numerical Value Assignment
The assignment of numerical values to potential
responses to all questions was a subjective, judgemental
process. The main consideration was that the assignment
would provide a relative measurement—a measurement that
would indicate the respondent's position on each variable
scale. The response values for all the questions are shown
in appendix D.
Questionnaire Construction
The questionnaire layout was designed especially for
ease of use. It also was aimed at improving participation
and completeness. The ease of completion was achieved by
providing check-off blanks and spaces for responses.
71
The importance of the research and the individual
participation were stressed in the cover letters. The let-
ters also promised confidential handling of the information.
A summary of results was promised too. A name and mailing
address on the questionnaire, to request a summary, was
provided by 86 percent of the repondents.
Survey Implementation
Pilot Study
The initial questionnaire was distributed to members
of the North Texas Chapter of the American Production and
Inventory Control Society, in order to conduct a pilot
study. This study was aimed at increasing question relia-
bility, relevance and understanding. Based on the results
of the pilot study several changes in the questionnaire were
made.
Questionnaire Mailing and Follow-Up
The cover letters for the first, second, and third
mailings are contained in appendices A, B, and C. A sub-
sequent mailing went to those not responding to an earlier
request. The third mailing utilized certified letters in
order to improve the rate of return. The first mailing
included 296 questionnaires. Sixteen questionnaires were
returned unfilled due to plant closing, lack of applica-
bility and inability to participate.
All efforts of mailings and telephone calls yielded a
72
return of 137 questionnaires (48.9 percent of the 280
eligible plants). Numerous phone calls were made in order
to complete and correct questionnaires. As a result there
were 119 usable returns (42.5 percent). Responses to the
mailings are shown in table 1.
TABLE 1
QUESTIONNAIRE RATE OF RETURN
Mai 1ing Number of Usable Responses
Percentage of Respondents
Percentage of Eligible P1 ants
First 70 58.8 25.0
Second 31 26.1 11.1
Third 18 15. 1 6.4
Total 119 100.0 42.5
Summary of Participants
This section contains tables which provide basic char-
acteristics of the participants and basic statistics
concerning the intensity and effectiveness variables.
Tables 2, 3, and 4 classify the respondents according
to their demographic characteristics. Tables 5 and 6 provide
the value of statistics for intensity and effectiveness
variables respectively. Table 5 contains seven intensity
variables and a total intensity score. The total intensity
score for each respondent was developed by summing the
73
scores for each of the seven variables. For all the seven
variables scores were positive integers. For all variables,
a higher score indicated higher intensity. A total effec-
tiveness score was not developed due to: (i) six of the
effectiveness scores were measured in percents while one was
measured in positive integers; and (2) a higher percent
indicated higher effectiveness in some variables and lower
in others. A full spectrum of scores occured in six of the
seven effectiveness variables and only in three of the seven
intensity variables, possibly due to different levels of
interdependence within the two variable groups. Further
analysis of the information contained in tables 2 through 6
is found in chapter five.
Appendix F provides the questionnaire response fre-
quencies. In the questionnaire there were several places in
which "other" was a possible choice. In question I B, ten of
the respondents answered in this manner. Some of the
specific responses were: estimates, MTM, ratio delay, and
video analysis. In question II B the category "other" was
used sixty-one times. Some of the more frequent responses
were: customer requirements (14), FIFO (7), and marketing
(5). In question II D there were sixteen responses in the
"other" category. The frequent responses were: production
control (4), joint decision (4), and customer (3). In
question III A there were five such responses, three were
lead time and two were contract requirements. The "other"
74
catgory drew fifty-nine responses in question V C. Thirty
of the respondents provided "not applicable" as an answer
and were assigned a score of zero. Some of the remaining
responses were: material availability (5), machine availa-
bility (3), and efficiency (3). In question VII B "other"
was marked thirty-one times. Twenty of those were indicated
as "not applicable" (zero score). Of the remaining eleven
reponses, capacity (2) and rescheduling (2) were the most
frequent.
TABLE 2
75
RESPONDENTS CLASSIFIED BY A TWO-DIGIT STANDARD INDUSTRIAL CODE
Two-Digit Standard Industrial Code
Nuaber of Respondents
Percentage of Respondents
20 11 9.2
21 0 0.0
22 3 2.5
23 9 7.6
24 1
00 • o
25 2 1.7
26 1 0.8
27 2 1.7
28 4
< •
CO
29 1 0.8
30 3 2.5
31 1 0.8
32 2 1.7
33 9 7.6
34 18 15. 1
35 4 3.4
36 19 16.0
37 9 7.6
38 1 0.8
39 19 16.0
Total 119 100.0
Note: See Appendix D, question IX B.
TABLE 3
RESPONDENTS CLASSIFIED BY NUMBER OF EMPLOYEES
76
Number of Employees Number of Respondents
Percentage of Respondents
500-1000 101 84.9
1001-1500 5 4.2
1501-2000 3 2.5
2001-2500 4 3.4
Over 2500 6 5.0
Total 119 100.0
77
TABLE A
RESPONDENTS CLASSIFIED BY TYPE OF OPERATION
Type of Operation Number of Respondents
Percentage of Respondents
Manufacture to stock onl y 6 5.0
Manufacture to order only 33 27.7
Manufacture to stock and to order 80 67.2
Total 119 100.0
78
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CHAPTER V
SURVEY ANALYSIS
The data obtained from the questionnaires was analyzed
utilizing several multivariate data analysis techniques. The
statistical analysis was performed on a Honeywell main frame
x I
computer, using the SPSS Information Analysis System. The
different tools are briefly described and followed by the
results of each phase of the analysis. In the final
section, a synthesis of the overall analysis is presented.
Factor Analysis
Factor analysis is a class of multivariate statistical
techniques. The main objective of these techniques is to
condense the information contained in several variables into
a smaller set of factors where the loss of information is
minimal. Factor analytic techniques are interdependence
techniques in which all variables are simultaneously consi-
dered. The differentiation between dependent and independ-
ent variables is not required. While there are a variety of
types of factor analysis, this dissertation utilized the
principle factor solution, with iteration and the varimax
orthogonal rotation. The selection of the type of factor
1986)
1SPSS X User's Guide. 2d ed. (New York: McGraw-Hill,
80
8 1
analysis is based on the specific research objectives. The
technique employed was primarily aimed at defining relation-
ships between variables.
Factor Analysis Applications
Factor analysis was applied three times. The first
application was done on both the intensity and effectiveness
variables (fourteen variables). The second application was
done on the intensity variables alone (seven variables).
The third application was done on the effectiveness varia-
bles alone (seven variables).
Corre 1 at i on Matr i ces
The principle factor analysis was applied to a matrix
of correlation coefficients among all the variables. The
correlation matrix used in the fourteen-variab1e factor
analysis is presented in table 7.
The principle diagonal of the matrix contains commu-
nal ity estimates. The estimate used here was the squared
multiple correlation coeffcient (SMC) of one variable with
all others. The SMC multiplied by 100 measures the percent-
age of variation that could be explained for one variable
from all others. For routing information, the SMC is 0.45.
This means that 45 percent of the routing information data
can be predicted from data on the remaining thirteen
var iab1es.
The correlation matrix was used in the first step of
82
the analysis. Table 8 shows the correlation matrix used in
the factor analysis of the seven-variable intensity data.
Table 9 shows the correlation matrix used in the factor
analysis of the seven-variab1e effectiveness data. Addi-
tional intermediary statistics are required for factor
solution but are not normally interpreted. They are pre-
sented in appendix G (tables 39-43).
Unrotated Factor Matrices
Two different factor matrices are presented for each
of the three factor analyses. The first set includes the
unrotated factor matrices which are normally shown without
interpretational comments. The second set includes the
rotated factor matrices which are subjected to interpre-
tation.
The fourteen-variab1e, seven intensity variables, and
seven effectiveness variables unrotated factor loadings
matrices are shown in tables 10, 11, and 12 respectively.
Table 10 is used in the following conceptual explanation.
Columns define the factors while rows refer to vari-
ables. At the intersection of rows and columns are the
loadings for the row variables on the column factor. The
factors are meaningful independent patterns of relationship
among variables. The number of factors extracted was a
variable controlled by the researcher. The criterion uti-
lized in stopping the iterative procedure of factor extrac-
tion was a minimum value allowed for the eigenvalue of a
83
subsequent factor. A minimum eigenvalue of 1.4 was selected
for the fourteen-variab1e analysis. For the seven intensity
variables analysis the eigenvalue was 1.0, and for the seven
effectiveness variables analysis it was set at 1.2. If the
eigenvalue was less than the value set by the researcher
factoring was terminated and rotation was commenced. Three
factors were extracted from the fourteen-variab1e analysis
(table 10), two factors were extracted from the seven inten-
sity variables analysis (table 11), and two factors were
extracted from the seven effectiveness variables analysis
(table 12).
Loadings, that can be interpreted like correlation
coefficients, measure which variables were invloved in which
2
factor pattern and to what degree. The column headed nh n
is refered to as the communality. This is the proportion of
a variable's total variation that is involved in the factor
patterns. It is the sum of the squared factor loadings. 2
The complement of communality (1 - h ) represents the pro-
portion of unique variance of a variable, the proportion not
explained by the factors or any other variable in the
analysis. 2
The ratio of the sum of the values in the h column to
the number of variables, multiplied by 100, equals the
percentage of total variation in the data that is explained
by the three factors. In table 10 the three factors
involved 35.9 percent of the data variation.
84
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TABLE 10
FOURTEEN-VARI ABLE UNROTATED FACTOR LOADINGS MATRIX
87
Variab1e Factors
h 2
F1 F 2 F3
1. Production standards .58 .35 -.18 .49
2. Priority determination .04 .56 .28 .39
3. Delivery dates determination .33 .09 .52 .39
4. Material requirements planning .63 -.07 . 19 .44
5. Routing information .30 -.06 .47 .31
6. Capacity utilization .38 .46 .06 .36
7. Backlog measurement -.18 .59 .04 .38
8. Delivery dates performance .62 -.36 -.08 .52
9. Lead times .23 -.20 -.25 . 16
10. Subcontract work .08 .02 .21 .05
11. Direct labor overtime -.26 -.29 .23 .20
12. Direct labor efficiency .50 . 11 -.41 .43
13. Plant and equipment uti1ization . 16 -.59 .42 .55
14. Work in process inventory -. 11 .23 .53 .35
Total variance (X) 13.60 12. 10 10.20 35. 90
Common variance (%) 37.88 33.70 28.42
Eigenvalues 1.91 1.69 1.43
TABLE 11
SEVEN INTENSITY VARIABLES UNROTATED FACTOR LOADINGS MATRIX
88
Variab1e Factors
h 2
F1 F 2
1. Production standards .59 -.03 .35
2. Priority determination .50 .51 .51
3. Delivery dates determination .49 -.25 .30
4. Material requirements planning .53 -.54 .56
5. Routing information .42 -.40 .34
6. Capacity utilization . 54 .35 .41
7. Backlog measurement .22 .65 .47
Total variance (X) 23.20 18.80 42.00
Common variance (A) 55.24 44.76
Ei genva1ues 1.62 1.31
TABLE 12
SEVEN EFFECTIVENESS VARIABLES UNROTATED FACTOR LOADINGS MATRIX
89
Variab1e Factors
h 2
Fi F 2
1. Delivery dates performance .76 .01 .58
2. Lead times .56 . 10 .32
3. Subcontract work -.07 . 13 .02
4. Direct labor overtime . 14 .70 .51
5. Direct labor efficiency .43 -.57 .51
6. Plant and equipment uti1ization .46 .53 .49
7. Work in process inventory -.34 .42 .30
Total variance (%) 20.50 18.50 39.00
Common variance (%) 52.56 47.44
Eigenvalues 1.43 ! 1.30
90
The "percent total variance" values reflect the per-
centage of total variation among the variables that is
related to each factor. The first unrotated factor delin-
eated the largest pattern of relationships in the data.
Subsequent factors depicted decreasing patterns. In table
10, factor 1 explained 13.6 percent of the total variance
among the variables. This is 37.80 percent of the variance
involved in all the three factors and is shown as a "percent
common variance" value. The eigenvalues equal the sum of
the column of square loadings for each factor, and measure
the amount of variation accounted by the factor pattern.
Rotated Factor Matrices
In the next step, factors were allowed to rotate. The
orthogonal rotation used in this research positioned factor
vectors, so that they have relatively high loadings from
relatively few variables. The rotation made it easier to
depict conceptual properties of each factor if they did in
fact exist. It should be noted though, that the amount of
explained variance was not altered by the rotation. The
varimax rotation was utilized to simplify the factors.
The fourteen-variable, the seven intensity variables,
and the seven effectiveness variables varimax rotated
matrices are placed in tables 13, 14, and 15 respectively.
By comparing the unrotated and rotated matrices (tables 10
and 13 for the fourteen-variable analysis; tables 11 and 14
for the seven intensity variables analysis; and tables 12
TABLE 13
FOURTEEN-VARI ABLE VARIMAX ROTATED FACTOR LOADINGS MATRIX
91
Variable Factors
h 2
F1 F 2 F 3
1. Production standards .68 .06 . 12 .49
2. Priority determination .25 -.52 .25 .39
3. Delivery dates determination .09 -.07 .61 .39
4. Material requirements pianning .34 .31 .47 .44
5. Routing information -.00 .05 .56 .31
6. Capacity utilization .51 -.21 .23 .36
7. Backlog measurement .20 -.58 -.08 .38
8. Delivery dates performance .26 .63 .25 .52
9. Lead times . 14 .35 -. 10 . 16
10. Subcontract work -.01 -.05 .22 .05
11. Direct labor overtime -.44 .03 .08 .20
12. Direct labor efficiency .58 .29 -. 11 .43
13. Plant and equipment uti1ization -.40 .43 .46 .55
14. Work in process inventory -.15 -.41 .40 .35
Total variance (%) 12.49 12.28 11. 13 35.90
Common variance (X) 34.79 34.20 31.01
Eigenvalues 1.75 1.72 1.56
TABLE 14
SEVEN INTENSITY VARIABLES VARIMAX ROTATED FACTOR LOADINGS MATRIX
92
Variab1e Factors
h 2
F1 F 2
1. Production standards .48 .34 .35
2. Priority determination .07 .71 .51
3. Delivery dates determination .54 . 11 .30
4. Material requirements planning .74 -.09 .56
5. Routing information .58 -.05 .34
6. Capacity utilization .20 .61 .41
7. Backlog measurement -.23 .65 .47
Total variance (%) 21.43 20.57 42.00
Common variance (%) 51.02 48.98
Eigenvalues 1.50 1.44
TABLE 15
SEVEN EFFECTIVENESS VARIABLES VARI MAX ROTATED FACTOR LOADINGS MATRIX
93
Variable Factors
h 2
Fi F2
1. Delivery dates perforiance .67 -.35 .58
2. Lead times .54 -. 18 .32
3. Subcontract work .01 . 15 .02
4. Direct labor overtime .45 .56 .51
5. Direct labor efficiency .11 -.70 .51
6. Plant and equipment uti1ization .65 .25 .49
7. Work in process inventory -.11 .53 .30
Total variance (X) 20.00 19.00 39. OO
Common variance (X) 51.29 48.71
Eigenvalues 1.39 1.32
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and 15 for the seven effectiveness variables analysis), it
2
was determined that the h values, the number of factors,
and the sum of the eigenvalues do not change with orthogonal
rotation.
Results and Conclusions
Table 16 is a summary of the rotated and unrotated
loadings in the three analyses. It is presented in order to
make the six-way comparison easier. Table 17 was developed
from the rotated factor loadings in the fourteen-variabIe
analysis. It lists the variables in descending order of
magnitude. Tables 18 and 19 contain similar information for
the two seven-variable analyses.
The fourteen-variab1e factor analysis contained more
data and resulted in a more meaningful output. The follow-
ing conclusions were drawn from that analysis (table 17):
1. Of the three factors depicted by the analysis,
factors 1 and 3 were heavily loaded by intensity variables,
and only slightly loaded by effectiveness variables. In
factor 2 the situation was reversed. It described heavy
loading by effectiveness variables, while the intensity
variables loadings were very light. The analysis apparently
confirmed the distinction between the intensity variables
and the effectiveness variables.
2. In factor 1, three of the four highest loadings
belonged to the following intensity variables: production
standards (0.68), capacity utilization (0.51), and material
96
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TABLE 18
SEVEN INTENSITY VARIABLES ROTATED LOADINGS LISTED BY MAGNITUDE
Factor i Factor 2
Haterial requirements Priority determination .71 planning .74
Backlog measurement .65 Routing information .58
Capacity utilization .61 Delivery dates
determination .54 Production standards .34
Production standards .48 Delivery dates determination . 11
Capacity utilization .20 Routing information -.05
Priority determination .07 Material requirements
Backlog measurement -.23 planning -.09
Eigenvalue Ei genvalue 1.50 1.44
TABLE 19
SEVEN EFFECTIVENESS VARIABLES ROTATED LOADINGS LISTED BY MAGNITUDE
98
Factor 1 Factor 2
De11very dates Direct labor overtime .56 performance .67
Work in process Plant and equipment inventory .53
utiIization
in CD •
Plant and equipment Lead times .54 uti1ization .25
Direct labor overtime .45 Subcontract work . 15
Direct labor efficiency . 11 Lead times 18
Subcontract work .01 Delivery dates performance -.35
Work in process inventory -. 11 Direct labor
eff iciency -.70
Eigenvalue Eigenvalue 1.39 1.32
99
requirements planning (0.34). In factor 3 the three highest
loadings also belonged to intensity variables: delivery
dates determination (0.61), routing information (0.56), and
material requirements planning (0.47). The fact that the
variable material requirements planning was common to both
factors made the conceptual properties of each factor less
discernible. In spite of that, a thorough examination of
the meaning of the other two heavy loading variables in each
factor resulted in the identification of two patterns.
Factor I was labeled intensity of capacity management--
internal factors, while factor 3 was labeled intensity of
capacity management--externa1 factors.
3. In factor 2, the three heaviest loadings belonged
to effectiveness variables: delivery dates performance
(0.63), plant and equipment utilization (0.43), and lead
times (0.35). The labeling of factor 2 as manufacturing
effectiveness was obvious.
The two seven-variable factor analyses contained less
data input and less meaningful output. The following conclu-
sions were drawn from the intensity variables analysis
(table 18):
1. Comparing the two factors in this analysis
revealed that the order of the variables in them was basi-
cally reversed. The three variables at the top of the list
in factor 1, were the same variables as those at the bottom
of the list in factor 2. At the same time the top three
100
variables in factor 2 were at the bottom of the list in
factor 1.
2. The comparison of factor 1 in this analysis to
factor 3 in the fourteen-variab1e analysis, revealed that
the three variables loading heaviest on both factors were
identical. The comparison of factor 2 in this analysis with
factor 1 in the fourteen-variab1e analysis, revealed the
following: three of the four variables loading heaviest on
factor 2 in this analysis and three of the four intensity
variables loading heaviest on factor i in the fourteen-
variable analysis were identical. As a result the factors in
this analysis were labeled in the same manner as the corre-
sponding factors in the fourteen-variab1e analysis. Factor
1 in this analysis was labeled intensity of capacity manage-
ment—external factors while factor 2 was labeled intensity
of capacity management--interna 1 factors.
A comparison between the fourteen-variab1e application
and the seven intensity variables application was made. It
was recognized that both delineated similar results.
The following conclusions were drawn from the effec-
tiveness variables analysis (table 19):
1. Comparing the two factors in this analysis re-
vealed that the order of the variables in them was basically
reversed. Two of the three variables at the top of the list
in factor one, were the same variables as two of the three
at the bottom of the 1ist in factor 2.
101
2. The comparison of factor 1 in this analysis to
factor 2 in the fourteen-variab1e analysis revealed that the
three variables loading heaviest on both factors were iden-
tical and in exactly the same order. The comparison of
factor 2 in this analysis to factor 2 in the fourteen-
variable analysis revealed that the order of their effec-
tiveness variables were basically reversed. Factor 1 in
this analysis was labeled manufacturing effectiveness-
external factors, while factor 2 was labeled manufacturing
effectiveness—internal factors. The fact that the variable
plant and equipment utilization loaded heavy on both factors
in this analysis, made their conceptual properties less
di scernib1e.
Factor analysis will be discussed again in this dis-0
sertation. When mentioned, reference will always be made to
the fourteen-variab1e application.
Canonica1 Corre 1 ation
Canonical correlation is a technique used to predict
several dependent variables form several independent
variables. The main objective of canonical correlation is to
simultaneously correlate the two sets of variables producing
a canonical function. In this study the intensity variables
were the independent set and the effectiveness variables
were the dependent set.
The results of the analysis indicated that the inde-
102
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103
pendent set had a significant impact on the dependent set.
The canonical correlation statistics are contained in table
20. The canonical correlation was moderate (0.47). The
highest coefficients in the canonical function in the
independent set, belonged to material requirements planning
(0.71) and production standards (0.55). In the dependent
set, the highest coefficient belonged to delivery dates
performance (0.69) and plant and equipment utilization
(0.48). The two intensity variables that were identified
had the highest influence on the effectiveness variables.
The two effectiveness variables that were identified had the
highest association with the intensity variables.
Bivariate Correlation
The Pearson product moment correlation coefficients
are contained in table 21. Only coefficients having a
significance of 0.05 or better will be discussed. The
primary attention was given to significant correlation coef-
ficients between intensity variables and effectiveness
variables. Significant coefficients within each variable
group was of a secondary importance.
The production standards (an intensity variable) had a
0.159 correlation coefficient with delivery dates per-
formance and a 0.259 correlation coefficient with direct
labor efficiency (both effectiveness variables). Material
requirements planning (intensity variable) had a 0.358
104
correlation coefficient with delivery dates performance
(effectiveness variable). Routing information (intensity
variable) had a 0.211 correlation coefficient with plant and
equipment utilization (effectiveness variable). Capacity
utilization (intensity variable) had a -0.184 correlation
coefficient with direct labor overtime (effectiveness
variable). Backlog measurement (intensity variable) had a
-0.264 correlation coefficient with plant and equipment
utilization (effectiveness variable).
The capacity utilization variable showed the strongest
relationship to other variables within the seven intensity
variable group. As could be expected, the total intensity
score was consistently significantly correlated with the
seven intensity variables. The direct labor efficiency
exhibited the strongest relationship within the seven effec-
tiveness variable group.
Tables 22 through 24 contain similar coefficients
calculated from data supplied by plants from three different
industries. These tables identified more significant rela-
tionships between intensity and effectiveness variables than
the total data.
Table 22 relates to the eighteen respondents that are
classified under fabricated metal products, except machinery
and transportation equipment (SIC 34). Production standards
(an intensity variable) had a -0.695 correlation coefficient
with work in process inventory (an effectiveness variable).
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109
Priority determination (an intensity variable) had a -0.516
correlation coefficient with subcontract work (an effective-
ness variable). Delivery dates determination (an intensity
variable) had a 0.423 correlation coefficient with subcon-
tract work and a 0.473 correlation coefficient with direct
labor overtime (both effectiveness variables). Routing
information (an intensity variable) had a 0.405 correlation
coefficient with subcontract work and a 0.605 correlation
coefficient with plant and equipment utilization (both
effectiveness variables). Capacity utilization (an inten-
sity variable) had a 0.521 correlation coefficient with
direct labor efficiency (an effectiveness variable).
Backlog measurement (an intensity variable) had a 0.343
correlation coefficient with delivery dates performance (an
effectiveness variable). Total intensity score had a 0.420
correlation coefficient with delivery dates performance, a
0.450 correlation coefficient with plant and equipment uti-
lization, and a -0.470 correlation coefficient with work in
process inventory (all effectiveness variables).
Table 23 relates to the nineteen respondents that are
classified under electrical and electronic machinery, equip-
ment, and supplies (SIC 36). For this group there were six
significant correlations between intensity and effectiveness
variables. Work in process inventory (an effectiveness
variable) had a 0.511 correlation coefficient with delivery
dates determination, a 0.471 correlation coefficient with
110
capacity utilization, and a 0.575 correlation coefficient
with total intensity score (all intensity variables). Table
24 relates to the nineteen respondents that are classified
under miscellaneous manufacturing industries (SIC 39). For
this group ther were nine significant correlations between
intensity and effectiveness variables. Delivery dates
performance (an effectiveness variable) had a 0.530 correla-
tion coefficient with production standards, a 0.417
correlation coefficient with material requirements planning,
and a 0.465 correlation coefficient with total intensity
score (all intensity variables). Subcontract work (an
effectiveness variable) had a -0.525 correlation coefficient
with routing information, a -0.444 correlation coefficient
with capacity utilization, a -0.614 correlation coefficient
with backlog measurement, and a -0.541 correlation coeffi-
cient with total intensity score (all intensity variables).
Multiple Linear Regression
Multiple linear regression is used to analyze the
relationship between a single dependent variable and several
independent variables. In this study the seven intensity
variables were regressed against each of the seven effec-
tiveness variables. As a result, seven regressions were
performed. Three of the regressions did not yield any
significant findings at the 0.05 level. The other four
regressions yielded very limited amounts of significant
findings. The results are presented in tables 25 through 28.
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113
Material requirements planning explained 12.8 percent
of the delivery dates performance variance (table 25).
Capacity utilization explained only 3.3 percent of the
direct labor overtime variance (table 26). Production stan-
dards explained 6.6 percent of the direct labor efficiency
variance (table 27). Backlog measurement explained 6.9
percent and routing information an additional 3.6 percent of
the plant and equipment utilization variance (table 28).
Cross-Tabu 1 ation
In addition to using quantitative statistical tools a
more qualitative descriptive analysis of the data is also
useful. Figures 1 through 15 present the distribution of
participants* scores on each of the seven intensity
variables, the total intensity score and the seven effec-
tiveness variables. Tables 29 and 30 contain a class-
ification of the scores by two of the three demographic
characteristics. Classification by the Standard Industrial
Code (SIC) is not presented. Due to the large number of
categories in this factor findings were meaningless. As far
as size (number of employess) is concerned, the medium
plants scored most effective in three out of seven catego-
ries. Those plants had the highest intensity scores in four
out of seven categories and in the total intensity score
(table 29). In the type of operation classification the
manufacture to stock only plants scored most effective in
four out of seven categories (table 30).
114
Each of tables 31, 32, and 33 present a classification
of the respondents by a pair of demographic characteristics.
These tables clearly demonstrate the fact that the number of
observations in the cells is very disproportionaI. This had
created some difficulty in interpretation of analysis of
variance designs. A major cause of the difficulty origi-
nated from the fact that the SIC factor had twenty catego-
ries. A meaningful way for subgrouping categories could not
be found. Helpful information about the questionnaire re-
sponse frequencies is contained in appendix F.
As time frame is concerned, all measurements were
related to current conditions. An attempt was made though
to provide a limited dynamic dimension to the study. While
all variables utilized questions to provide current measure-
ment, two effectiveness variables were equipped with two
questions each. The two questions were designed to provide
measurement of the past as well as present conditions. The
effectiveness variables involved are the subcontract work
and the direct labor overtime. For the subcontract work
variable, question VIII D related to the current year while
question VIII C related to the year before. For the direct
labor overtime variable the questions were VIII F and VIII E
respectively. Two tests of significance for the scores
means, one for each variable, resulted in the conclusion
that there was no significant difference between the score
means in the two time periods.
115
Respondents
30~
30
25
20
15
10
15
25
17
9 9
Scores A 5 6 8 9
Fig. 1. Distribution of scores for the production standards variable (mean = 4.639; median = 5.000; skewness = -0.264).
116
Respondents
30~
25
20
15
10
23
9
19 18
16
12
10
Scores A 5 8 9
Fig. 2. Distribution of scores for the priority deter-mination variable (mean = 4.723; median = 5.000; skew-ness -0.027).
117
Respondents 36
35
30
25
34
20 18
15 13
10
10 8
Scores 3 4 6
Fig. 3. Distribution of scores for the delivery dates determination variable (mean = 3.622; median = 4.000; skewness = -0.019).
118
53
Respondents
30
25 23
20
15
10
14
Scores 5 6 8 9 10 11
Fig. 4. Distribution of scores for the material require-ments planning variable (mean = 7.672; median = 9.000; skewness = -0.552).
119
Respondents
35
30
25
37
25
20 18 18
15
10 9
Scores 4 5 8
Fig. 5. Distribution of scores for the routing information variable (mean = 4.739; median = 5.000; skewness = -0.264).
120
42 Respondents
25
20
26
15 13 13
10 8
Scores 3 4
Fig. 6. Distribution of scores for the capacity utilization variable (mean = 4.387; median = 4.000; skewness = -0.386).
121
Respondents
25 24
23
20
15
10
21 20
17
6 Scores 7 8 9 10 11 12
Fig. 7. Distribution of scores for the backlog measurement variable (mean = 7.504; median = 9.000; skewness = -1.233).
122
Respondents
30
25
20
15
10
31
27
11 10
21
12
10 15 20 Scores
25 30 35 40 45 50 55
Fig. 8. Distribution of scores for the summation of the seven capacity management intensity variables (mean = 37.286; median = 38.000; skewness = -0.371).
123
45 Respondents
*
25
20
15
10
20
13
6
18
14
40 55 70 Scores 80 85 90 95 100 (Percent)
Fig. 9. Distribution of scores for the delivery dates performance variable (mean = 87.487; median = 93.000; skew-ness = -1.796).
124
37 Respondents
35
30
25
20 17
16 15 15
15
10 9
10
25 45 Scores
65 75 85 95 100 (Percent)
Fig. 10. Distribution of scores for the lead times variable (mean = 60.025; median = 55.000; skewness = -0.040).
125
Respondents
Scores 15 25 35 100 (Percent)
Fig. 11. Distribution of scores for the subcontract work variable (mean = 7.008; median = 5.000; skewness = 6.091).
126
Respondents 58
50
30
25
20
15
10 8
Scores 15 25 35 45 lOO (Percent)
Fig. 12. Distribution of scores for the direct labor overtime variable (mean = 8.739; median = 10.000; skewness 2.214).
127
37 Respondents
35
30
25
20
15
10
17
8
23
20
14
50 65 Scores
75 85 90 95 100 (Percent)
Fig. 13. Distribution of scores for the direct labor efficiency variable (mean = 82.958; median = 80.000; skew-ness = —0.666).
128
Respondents
30
30
25 23
20
20
16
15
9 9 10
Scores 9 10 14 15 21
Fig. 14. Distribution of scores for the plant and equipment utilization variable (mean = 9.933; median = 10.000; skewness = 0.387).
129
Respondents
34 35
30
25
20
15
10
32
19 18
13
15 30 Scores 45 60 75 100 (Percent)
Fig. 15. Distribution of scores for the work in process inventory variable (mean = 35.504; median = 22.000; skewness = 1.109).
130
TABLE 29
SCORES CLASSIFIED BY NUMBER OF EMPLOYEES
Variable 500 to 1000
1001 to 1500
1501 to 2000
2001 to 2500
Over
2500
Production standards 4.63 1-9
3.20 1-5
5.00 4-6
7.25 6-9
4.00 2-7
Priority deteraination 4.75 0-9
3.20 1-7
7.00 6-8
5.00 2-9
4.17 2-8
Delivery dates determination
3.55 1-6
4.20 1-6
5.00 4-6
3.75 2-6
3.50 1-6
Ma ter i a1 requ i resents planning
7.49 0-11
7.80 0-11
9.67 7-11
9.50 7-11
8.50 7-11
Routing inforaation 4.74 0-8
3.80 3-6
5.33 3-9
4.25 3-7
5.50 3-7
Capacity utilization 4.36 0-7
5.00 2-7
7.00 7-7
3.25 0-7
3.83 1-7
Backlog aeasureaent 7.21 0-11
6.60 0-10
10.00 8-12
10.00 8-11
10.33 8-12
Total intensity score 36.73 12-53
33.80 28-42
49.00 45-51
43.00 32-49
39.83 32-47
Delivery dates perforaance
89.90 40-97
87.40 75-97
94.00 88-97
90.25 83-97
92.33 83-97
Lead tiaes 58.46 25-97
78.40 55.97
65.00 35-80
71.75 55-97
60.83 25-80
Subcontract work 6.55 5-67
17.40 5-67
5.00 5-5
5.00 5-5
8.33 5-20
Direct labor overtiae 8.42 5-30
14.00 5-30
8.33 5-10
11.25 5-20
8.33 5-10
Direct labor efficiency 83. 19 57-97
76.80 57-97
85.33 80-88
90.50 88-93
78.00 70-88
Plant and equipaent uti1ization
9.81 3-18
10.80 5-18
6.67 5-10
10.50 5-15
12.50 5-18
Uork in process inventory
35.20 15-87
34.60 22-53
48.00 38-53
26.25 15-53
41.33 15-87
Nuaber of cases 101 5 3 4 6
Note: (Mean/Mi ni aiua-Max i nun )
131
TABLE 30
SCORES CLASSIFIED BY TYPE OF OPERATION
Variable Mfg. to Mfg. to Mfg. to
Variable Stock Order Stock and Only Only to Order
Production standards 3.83 4. 18 4.89 1-7 1-7 1-9
Priority determination 3.50 4.82 4.78 0-7 i-9 0-9
Delivery dates 2.83 3.73 3.64 determination i-6 i-6 1-6
Material requirements iO.33 8.09 7.30 planning 7-11 0-ii 0-11
Routing information 5.00 4.79 4.70 3-6 0-9 0-8
Capacity utilization 4.33 4.94 4. 16 3-7 0-7 0-7
Backlog measurement 5.33 8.09 7.43 0-10 0-11 0-12
Total intensity score 35.17 38.64 36.89 22-45 25-53 12-51
Delivery dates 94.67 88. 15 86.68 performance 83-97 40-97 40-97
Lead times 53.33 60. 12 60. 49 25-80 25-97 25-97
Subcontract work 17.00 7. 18 6. 19 5-67 5-67 5-30
Direct labor overtime 6.67 9.70 8.50 5-10 5-30 5-30
Direct labor efficiency 87.67 81.27 83.30 80-97 57-97 57-97
Plant and equipment 7. 17 10.21 10.03 uti1ization 5-15 3-18 3-18
Vork in process 29.33 41.94 33.31 inventory 15-87 15-87 15-87
Number of cases 6 33 80
Note: (Mean/Miniaua-Maxiaua)
132
TABLE 31
RESPONDENTS CLASSIFIED BY A TWO-DIGIT STANDARD INDUSTRIAL CODE AND NUMBER OF EMPLOYEES
Two-digit Standard Industrial Code
Nuabtr of Eaployees
Two-digit Standard Industrial Code 500
to 1000
1001 to 1500
1501 to 2000
2001 to 2500
Over
2500
20 8 2 1
21
22 3
23 9
24 1
25 2
26 1
27 1 1
28 4
29 1
30 3
31 1
32 2
33 8 1
34 17 1
35 3 1
36 11 2 1 2 3
37 7 2
38 1
39 18 1
TABLE 32
RESPONDENTS CLASSIFIED BY A TWO-DIGIT STANDARD INDUSTRIAL CODE AND TYPE OF OPERATION
133
TYPE OF OPERATION MANUFACTURE
Two-digit Standard Industrial Code To
Stock Only
To Order Only
To Stock and to Order
20 1 2 8
21
22 1 2
23 3 6
24 *1
25 2
26 1
27 2
28 1 1 2
29 1
30 3
31 1
32 2
33 3 6
34 7 11
35 4
36 1 8 10
37 4 5
38 1
39 4 15
TABLE 33
RESPONDENTS CLASSIFIED BY NUMBER OF EMPLOYEES AND TYPE OF OPERATION
134
TYPE OF OPERATION MANUFACTURE
Number of Employees To
Stock Only
To Order Only
To Stock and to Order
500-1000 4 24 73
1001-1500 1 3 1
1501-2000 2 1
2001-2500 1 3
Over 2500 —
1 l
3 2
135
In addition to the questions corresponding to the
study, personal background information about the partici-
pants was gathered. This information is contained in ques-
tions IX D through IX G of the questionnaire response
frequencies (appendix F). In question IX D, the category
"other" was chosen by fifteen respondents. Of those, nine
had a formal education in science, while only one had no
formal education. In question IX E, thirty-one chose the
category "other" that indicated a wide variety of profes-
sional associations, a majority of which were represented
only once. Those with higher frequency were: ASQC (4), ASPE
(3), ASME (2), and The American Foundrymen Society (2).
Only nine of the participants indicated in question IX G
that they have gained a professional certificate. Six out
of the nine certificates were identified as the CPIM,
awarded by the American Production and Inventory Control
Society. The title was identified by 116 of the 119 respon-
dents. The largest group included sixty-nine individuals
who were manufacturing managers at different levels. The
remainder included: top management (9), engineering manage-
ment (8), production control (7), material management (3),
quality control (2), and sales (2).
Cross-tabu 1 ation of the personal background informa-
tion versus effectiveness mean scores are presented in
Appendix H (tables 44-46).
136
TABLE 34
ONE-WAY ANALYSIS OF VARIANCE BY DEMOGRAPHIC CHARACTERI STICS
Variable Number of Employees
Two-Digit (SIC)
Type of Operation
Production standards — — —
Priority determination - - - - —
Delivery dates determination - - — —
Mater ia1 requi rements planning - - - - —
Routing information — - - - -
Capacity utilization - - - - - -
Back log measurement - - * —
Delivery dates performance - - — „
Lead times - - — - -
Subcontract work - - - - —
Direct labor overtime — —
Direct labor efficiency — — —
Plant and equipment uti1ization * * —
Work in Process Inv. — - - —
* R < .05
137
TABLE 35
TWO-WAY ANALYSIS OF VARIANCE BY DEMOGRAPHIC CHARACTER ISTICS
Source of Variation
By Number of Employees and a Two-Digit Standard Industrial Code
Variable
Main Effects
Joint Number of Employees
Two-Digit SIC
Two-Way Interaction
Production standards — —
Priority determination - - - - - - —
Delivery dates (1) - - - - - - —
Material requirements planning - - __
Routing information - - — — - -
Capacity utilization — - - - - •
Back 1og measurement * - - - - - -
Delivery dates (2) - - - - — —
Lead times - - - - - - - -
Subcontract work - - - - * *
Direct labor overtime - - - - - - - -
Direct labor efficiency - - - - - - - -
Plant and equipment uti1ization * — * _ _
Work in process inv. - - - - - - - -
* E < <05. Note: (1) = Determination, (2) = Performance
TABLE 36
TWO-WAY ANALYSIS OF VARIANCE BY DEMOGRAPHIC CHARACTERISTICS
1 3 8
Source of Variation
By Number of Employees and Type of Operation
Variable Main Effects
Two-Way Interaction
Variable
Joint Number of Employees
Type of Oper.
Two-Way Interaction
Production standards — — —
Priority determination — — — - - •
Delivery dates (i) - - - - - - - -
Material requirements pianni ng — — — —
Routing information - - — - - —
Capacity utilization - - - - - - - -
Back 1og measurement * — — - -
Delivery dates (2) - - - - — —
Lead times — — - - - -
Subcontract work - - - - ft
Direct labor overtime — — ft —
Direct labor efficiency — - - - - —
Plant and equipment uti1ization - - — —
Work in process inv. — — - - - -
* p <.05. Note: (1) = Determination, (2) « Performance
TABLE 37
139
TWO-WAY ANALYSIS OF VARIANCE BY DEMOGRAPHIC CHARACTERISTICS
Source of Variation
By Type of Operation and a Two-Digit Standard Industrial Code
Variable Main Effects
i
Joint Type of Operation
Two-Digit SIC
Two-Way Interaction
Production standards - - — — —
Priority determination — — — —
Delivery dates (1) — — » * *
Material requirements pianning - - - - —
Routing infornation — — » —
Capacity utilization - - — - - —
Backlog measurement * — ft —
Delivery dates (2) - - — - - —
Lead times - - — - - —
Subcontract work — - - * ft
Direct labor overtime — — — - -
Direct labor efficiency — - - - - —
Plant and equipment uti1izat ion * - - ft —
Uork in process inv. - - — — —
* fi < .05. Note: (1) = Determination, (2) = Performance
140
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141
Analysis of Variance
The material presented in the cross-tabulation section
is descriptive and does not lend itself to statistical
significance testing. In this section analysis of variance
CANOVA) techniques are utilized to test the cross-tabulation
results.
A one-way ANOVA was performed for the fourteen vari-
ables (seven intensity variables and seven effectiveness
variables) against each of the three demographic character-
istics. The results are shown in table 34. The plant and
equipment utilization (effectiveness variable) varied signi-
ficantly by plant size and the two-digit SIC. For the
backlog measurement (intensity variable), a significant •
difference existed only for the two-digit SIC.
In effort to further partition the effects of differ-
ent demographic characteristics, several multiple factor
ANOVA designs were performed. These designs included two-
way analyses (tables 35 through 37) and three way analysis
(table 38). In these analyses the variables that showed
significant variances most frequently were plant and equip-
ment utilization, subcontract work, backlog measurement and
delivery dates determination. Except for subcontract work
those variables loaded heavy on some of the factors that
were extracted in the factor analyses.
As indicated in the cross-tabulation section, the
disproportiona1 number of observations in each cell created
142
difficulty in interpretation. The limited findings should
be used cautiously.
Synthesis: Capacity Management Intensity
Production Standards
This variable measured the percent of plant operations
that were covered by time standards and the techniques
utilized to set them.
Distribution
Scores were distributed almost normally with 46 per-
cent of the participants scoring five or six. Skewness was
-0.264. Scores were influenced by the type of operation,
with manufacture to order scoring the highest.
Association
The variable loaded highest on the capacity planning
factor. It had a 0.240 correlation coefficient with
material requirements planning (intensity), and a 0.259
correlation coefficient with direct labor effciency (effec-
tiveness). In regression analysis the variable provided a
significant explanation for 6.6 percent of the direct labor
efficiency variance. In the canonical correlation it had the
second highest correlation coefficient of all intensity
var iab1es.
Priori ty Determination
This variable measured the percent of orders to which
143
priority codes are assigned and their frequency of change,
identified the priority system/s utilized and the authority
assigning them.
Distribution
Scores distribution was rather level in the two to
seven range. Skewness was minimal (-0.027). Plant size
influenced the scores, with the medium size plants scoring
higher than smaller or larger plants.
Associat ion
The variable had a 0.260 correlation coefficient with
capacity utilization (intensity). It loaded moderately on
both the capacity planning and capacity control factors.
Delivery Dates Determination
This variable measured the percentage of cases in
which a customer forecast was sought and identified the
method of delivery date determination.
Distribution
Scores distribution was almost normal with 59 percent
of the participants scoring three or four. Skewness was
negligible (-0.019). Plant size influenced the scores, with
a medium size plant scoring highest.
Association
The variable loaded highest on the capacity control
factor. It had a 0.195 correlation coefficient with the
144
material requirements planning variable (intensity).
Material Requirements Planning
This variable identified the existence of an MRP sys-
tem and measured it accuracy.
Distribution
The distribution of scores was trimodel with 76 per-
cent of the participants scoring three, seven, or eleven.
Scores were influenced by the plant size with the medium
size plants scoring highest and the extreme sizes scoring
1 owest.
Associat ion
The variable loaded fourth heaviest on the capacity
planning factor and third heaviest on the capacity control
variable. It had a 0.358 correlation coefficient with deli-
very dates performance (effectiveness). In the regression
analysis it explained 12.8 percent of the delivery dates
performance variance. In the canonical correlation it had
the highest correlation of all the intensity variables.
Routing Information
This variable measured the availability of routing
information and the factors dictating the selection of
alternative routings.
Distribution
While the posssible scoring range was zero to nine, 90
145
percent of the paticipants scored between three and seven.
Skewness was -0.264.
Association
The variable loaded second highest on the capacity
control factor. It had a 0.2ii correlation coefficiant with
the plant and equipment utilization variable (effective-
ness). In the regression analysis it explained 3.5 percent
of the plant and equipment utilization variance.
Capacity Utilization
This variable measured the availability of load infor-
mation and its use in changing delivery dates.
Distribution
Bunching occured at the extremes and the middle of the 0
scores distribution. Skewness was -0.386. The medium size
plant scored higher than the extreme sizes.
Associat i on
The variable loaded third highest on the capacity
planning factor. It had a 0.184 correlation coefficient
with the direct labor overtime variable (effectiveness). In
the regression analysis it explained 3.3 percent of the
direct labor overtime variance. The relationship was
negative.
Backlog Measurement
This variable measured the use of a backlog as a
146
planning and control tool.
Di str ibution
The distribution was almost normal, between five and
twelve. In addition 18 percent of the participants scored
zero. Skewness was negative (-1.223). The scores were
influenced by the plant size, with the largest plants
scoring highest.
Association
The variable had a 0.264 correlation coeffcient with
plant and equipment utilization (effectiveness). In the
regression analysis it provided an explanation for 6.9
percent of the plant and equipment utilization variance.
The relationship was identified as negative.
Total Intensity Score
This variable was produced by summing all the indivi-
dual intensity scores and provided an overall measure of
intens i ty.
Distribution
Scoring was almost normally distributed with a minimum
score of twelve and a maximum score of fifty-three.
Possible minimum was zero while the possible maximum was
sixty-eight. The distribution was skewed by -0.371. The
medium size plants' total score was higher than those of the
smaller or larger plants.
147
Associati on
As might be expected, this variable was consistently,
significantly correlated with the seven intensity variables.
Synthesis: Manufacturing Effecti veness
Delivery Dates Performance
This variable measured the percent of the time in
which promised delivery dates were met.
Distribution
The distribution was skewed (-1.796) so that the fre-
quencies increased as the scores increased. The medium size
plants scored higher than the smaller or larger plants.
Association
The variable loaded highest on the manufacturing
effectiveness factor. In the canonical correlation it had
the highest correlation coefficient of all effectiveness
variables. In regression analysis 12.8 percent of its
variance was explained by the material requirements planning
variable. It had a 0.358 correlation coefficient with the
material requirements planning and a 0.159 correlation coef-
fcient with production standards.
Lead Times
This variable measured the percent of the time in
which the respondent's lead times were shorter than those of
his competitors.
148
Distributi nn
The distribution was rather level except for 31 per-
cent of the paticipants scoring fifty-five. Skewness was at
a minimum. The type of operation influenced the scores with
the manufacture to stock and to order scoring highest.
Association
The variable loaded third heaviest on the manufactur-
ing effectiveness factor. It had a 0.166 correlation coef-
ficient with delivery dates performance (effectiveness).
Subcontract Work
This variable measured the percentage of output (in
dollars) that was subcontracted due to lack of capacity.
Distribution
The distribution was highly concentrated at the lower
side of the range with 87 percent of the participants
scoring five. Skewness was 6.091. The type of operation
influenced the score, with the manufacture to stock and to
order scoring most effective.
Association
The variable had a 0.165 correlation coefficient with
work in process inventory (effectiveness).
Direct Labor Overtime
This variable measured what percent of total direct
labor hours were overtime hours.
149
Pi stribution
The distribution was positively skewed (2.214). While
no participants scored forty or seventy-two, 49 percent
scored five. The medium size plants scored more effective
than the larger or smaller plants.
Association
In regression analysis 3.3 percent of the variance in
this variable was explained by the capacity utilization
variable (intensity). It had a -0.184 correlation coeffi-
cient with capacity utilization (intensity), and a 0.165
correlation coefficient with lead times (effectiveness).
Direct Labor Efficiency
This variable measured the overall direct labor effi-
ciency as a ratio between output at standard and actual
hours.
Distribution
The distribution was negatively skewed (-0.666) with
no participants scoring fifty. The manufacturing to stock
only plants scored most effective.
Association
In regression analysis 6.6 percent of the variance in
this variable was explained by production standards. This
variable had a 0.259 correlation coefficient with production
standards (intensity), and a 0.188 correlation coefficient
150
with the delivery dates performance (effectiveness).
Plant and Equipment Utilization
This variable measured the number of weekly shifts of
operation.
Distribution
The distribution was positively skewed (0.387). Plant
size influenced the scores with the largest plants scoring
hi ghest.
Associati nn
The variable loaded second highest on the manufactur-
ing effectiveness factor. In the canonical correlation it
had the second highest correlation coefficient of all the
effectiveness variables. In regression analysis 6.9 percent
of its variance was explained by backlog measurement while
an additional 3.5 percent was explained by routing informa-
tion. This variable had a -0.264 correlation coefficient
with backlog measurement (intensity) and a 0.211 correlation
coefficient with routing information (intensity).
Work in Process Inventory
This variable measured the percent of total inventory
value dedicated to work in process inventory.
Distributi on
The distribution was highly concentrated on the lower
side of the range with 55 percent of the participants
151
scoring fifteen or twenty-two. Plants manufacturing to
stock only scored most effective.
Association
The variable had a 0.165 correlation coefficient with
subcontract work (effectiveness).
CHAPTER VI
SUMMARY AND CONTRIBUTIONS
This chapter contains an explanation of the rejection
of the null hypothesis. It also presents the conclusions
from the survey results and suggestions for additional
research.
Hypothesis
The main objective of this study was to examine the
relationship between the intensity of short-range and
medium-range capacity management and the effectiveness of
manufacturing operations. Data were collected to test the
null hypothesis:
Hq The intensity of short-range and medium-range
capacity management does not influence manufacturing effec-
tiveness.
The results of this research did not adequately sup-
port the rejection of the null hypothesis. However, they
did definitely identify a distinct group of capacity manage-
ment intensity variables that influence manufacturing
effectiveness in specific cases. A summary of the findings
with a managerial orientation are presented below.
Intensity Variables
The intensity variables were placed in three groups
152
153
that identified how influential they were over the effec-
tiveness measures.
Most Influential
The variables in this group were: production standards
and material requirements planning. They were identified as
such by all the different statistical analyses that were
performed. The indication for the manufacturing manager is
to concentrate on improvements in these areas.
Moderately Influential
Members of this group were: the routing information
and the capacity utilization variables.
Least Influential
The intensity variables placed in this group were:
priority determination, delivery dates determination, and
backlog measurment.
Effectiveness Variables
The effectiveness variables were divided into three
groups. The groups identify the level at which the vari-
ables were influenced by the intensity variables. A higher
level of influence should indicate to the manufacturing
manager that he can exercise a better level of contol.
Highly Influenced
The variables identified in this group were the plant
and equipment utilization and delivery date performance.
154
Plant and Equipment Utilization
Plants with a higher plant and equipment utilization
rate had significantly better routing information, a finding
that is intuitively clear. Those plants were also found to
use backlog as a capacity planning tool less extensively, a
finding that is not intuitively clear. It is possible that
a higher rate of plant and equipment utilization represents
two different things: a greater absorption of overhead but a
less efficient operation. The factor analysis, canonical
correlation, and Pearson correlation supported the placing
of the variable in this group.
Delivery Dates Performance
For participating plants, those having a'better deliv-
ery date performance were significantly advanced in their
production standards and material requirements planning
system. The factor analysis, canonical correlation, and
Pearson correlation supported the placing of the variable in
this group.
Moderately Influenced
The variables that were placed in this group were
direct labor efficiency and direct labor overtime. The
factor analysis and canonical correlation supported the
placing of the variables in this group. For plants that are
not labor intensive this should not create a problem.
155
Least Influenced
This group was comprised of the following variables:
subcontract work, lead ti.es, and work in process inventory.
It is possible that these variables were subject to control
not only by manufacturing management but by forces fro.
other corporate functions.
Demographic Character 1 i
In regard to the type of operation and plant size,
findings were not only significant but could also be imple-
mented, subject to mainly external but also some internal
constraints.
Type of Operation
Participating plants that manufacture to stock only,
were identified as the most effective in four out of the
seven categories. The other two types of operation were
less effective probably due to the fact that they react to
the market more than they act.
Number of Employees
The optimum plant size, as far as effectiveness, was
the medium size. The larger and smaller plants were less
effective. This finding supports the concept of diseconomy
of scale beyond an optimum range, not only in regard to the
production function but the management function as well.
Two Digit Standard Industrial Code (SIC )
156
Due to the large number of categories, no significant
findings could be presented.
Future Research
The geographic expansion of this research to a
national survey may prove beneficial. At the same time, the
number of SIC's should be substantially reduced. Certain
variable scales should be altered in order to achieve better
proportionality of observations per cells. As a result
seveal surveys could be put into a c t i o n - o n e for each group
of SIC's that exhibit similarity in their operation.
Additional research could also include monetary
measures. It will facilitate a cost/benefit analysis. This
will ultimately enable a construction of a quantitative
model for the purpose of finding the point of optimal capac-
ity management costs and manufacturing effectiveness bene-
fits could be identified.
APPENDIX A
N O R T H TEXAS STATE U N I V E R S I T Y P . O . B O X 1 3 6 7 7
D E N T O N , T E X A S 7 6 2 0 3 - 3 6 7 7
157 D E P A R T M E N T OF M A N A G E M E N T
C O L L E G E o r B U S I N E S S A D M I N I S T R A T I O N
March 26, 1986
Dear Manufacturing Manager:
Md^?s° in f lSenc f
s e c t o r ' W i l 1 S t M d ° r f S l 1 0 n t^e s t rength of i t s . S & S S S
n a i r e t S u ' S n f ? f e V ^ « t l o n n ^ r y o J 0 r t n 0 S n ^ i n g y a C s i S d i n g
to t h i s study and to aStiemen? l i ? f r a t S f ^ ^ n L 2 ° n ^ i J U t i o n
for°yourCconvenience?d a d d r e 6 s e d " P 1 * i s enc lose?
IS? r s
p K L H S i l t r e l p o n s f i s t l g h ^ C £ L " t J o S l T t Y ? ! ^ ^ S e f S U W O r t °< t l i s ' s & T L T *
Sincerely,
Joseph Yehudai JY:oy
E n d s : Questionnaire Reply Envelope
A C S T 7 - 5 6 5 - 3 1 4 0 • D A L L A S - F T . W O R T H METRO 2 6 7 - 2 8 3 2
APPENDIX B
N O R T H TEXAS STATE UNIVERSITY P . O . B O X 1 3 6 7 7
D E N T O N , T E X A S 7 6 2 0 3 - 3 6 7 7
1 58 D E P A R T M E N T o r M A N A G E M E N T
C O L L E G E O F B U S I N E S S A D M I N I S T R A T I O N
May 5, 1986
Dear Manu fac tu r i ng Manager:
M d ^ t s ° i n f l u e n c e T " 1 ™ economy w i l l s tand o r f a l l on t he s t r e ^ t h f t * American s e c t o r . T h i s r e s e a r c h i s u ^ S e r w L now f J d ^ v T U f a C t u r i n g
o f the r e s u l t s w i t h o u t cos t j u s t l y D r o v i d i ™ a c o p J f
about your own o p e r a t i o n Oniv a "M™?* A § some i n f o r m a t i o n have been as™d t ? p £ ? ^ i S a t e L = t T b e L ° f C 0 D P « i ^ response i s h i g h l y 8 S t U d y ' t h e r e f ° ™ your
n a i r e 6 ^ u l m e ? ? n f ?S»®S t 0 c 0 ^ } e t e t h e enc losed q u e s t i o n -
have not y e t had a chance t o y o u # I f y ° u
if you would do so no!!? respond, I would be most gratefil
;;Si;S!i s „-sl-SE\.
S i n c e r e l y ,
Joseph Yehudai JY:oy
E n d s : Q u e s t i o n n a i r e Reply Envelope
A C S I 7 - 3 6 3 - 3 1 4 0 • O A L L A S - F T . W O R T H METRO 2 6 7 - 2 8 3 2
APPENDIX C
N O R T H TEXAS STATE U N I V E R S I T Y P . O . B O X 1 3 6 7 7
O C N T O N , T E X A S 7 6 2 0 3 - 3 6 7 7
D E P A R T M E N T O F M A N A G E M E N T
C O L L E G E o r B U S I N E S S A D M I N I S T R A T I O N
159
June 24, 1986
and its influence on manufactSing e f f e c t - m a n a S e m e n t f u n c t i o n
economy will stand or fall on the' £ i V e 2 e ? s # T h e American sector. This research is underway now 2Sd 1 ja^acturing of the results without cost i u s f b v m a y a v e a C 0 W
about your own operation. Only a lim?t*rf * f S O m e i n f o r m ation have been asked to participate ?n + 5® 0 C0mPanies response is highi? iSortSt h l S S t U d y ' b e f o r e your
naire? " t 0 t h e en<=l°«<i question-
M I •
« ^ R I O S S R . S E S T T O '
S S S ^ * 5 ^ « F T O E S S J 5 S £ O S I L T S T B .
would lik^to^hank^ou^n advance1" AUst°rt rff J5 i s s t u dy a111! envelope is enolosed'for j o ^ w ^ ^ n i t n l e T a d d r e s s e d r e P ^
Sincerely,
Joseph Yehudai JY:oy
Ends: Questionnaire Reply Envelope
A C 8 1 7 - 9 6 5 - 3 1 4 0 • D A L L A S - F T . W O R T H M E T R O 2 6 7 - 2 8 3 2
APPENDIX D
160
QUESTIONNAIRE RESPONSE VALUES
SUT?V£Y OF CAPACITY MANAGEMENT PRACTICE
I. PRODUCTION STANDARDS
' " S3SSTSiSJ *
B.
f t h a n ^ -£ Between 51 and 7 » J. Between 25 and 50* over 75*
J. Time study J. Historical records J. Standard data J. vork sampling _L Predetermined motion times J, other:
II. PRIORITY DETERMINATION
A* BSiJSSNSLa'Jsrorde" - ~i«M4 * «*««, £. Less turn 25* _2 Between 51 end 75* J. Between 25 and 50* Over 75*
B" (Sj«kySl°?hSiSplJ)B),St" l s utlll2'd l n your company?
_L Dynamic-critical ratios J, Other:
J_ Dynamic-order size J_ other:
_L Static-customer size
C # * Pri°rity level/code as market condition, dictate, after „ ord.J h „ b.en r . U . ^ tJ the shop?
-2> Y e e £ No
D* l2?el"olS? fc2«k'onS)rUy i n * S' 1 S n l n ! * Pr^ority
_L Sales Bept, JL Top management JL Manufacturing Dept. Other:
Jointly by Sales Dept. and Mfg. Dept
III. DELIVERY DATES
A* (check'one)""' deliT,r3f d , t e" are promised based on:
1 Customer request _1 Customer raquest subject to -tL. Available capacity available capacity
JL Other:_
161 B. What percent of the time do you seek and
customers) a forecast or an early warning nf 4 your to help you better meet their neLsfuSfck om> r'1ulrement6
_fl Less than 25% _£ Between 5. and 75* _1 Between 25 and 50# _ j j over 75#
IV. MATERIAL REQUIREMENTS PLANNING
A" S S C t t S j n S h K ! ™ " t e r i l 1 * - * » «
JJ'8 —2 Currently laplenentlng
B' iStlfKS °?;re'e c*P a c U' Planning system directly ( H R P ) M : h « i S h m % K t , S S y ) , q U i r e B r a t > P l a , m i n s ° 3 ' U m '
L Yes a "f -2 Do not have an MRP system
Do not hare a capacity planning system
C* Percent of your plant's products (as measured
ftkiossi05rou~,ccura?eMu«
_2 Less than 2.5% _£ Between 51 and 75% -1 Between 25 and 50# Over 75#
V. ROUTING INFORMATION
A" Fm MMufSC?Stj^iiSu? J1"'1'products/components, kas measured in dollars) do you have routine in form*fin* or operations sequence? (check one) information
_fl Less than 25* j, B,t,„n 5, M d ^
J. Between 25 and 50# Over 75#
B" ilLaiiernate sequences or alternate routing an integral part of your planning system? 6 integral
-2 Ies _Q No
C* !!S2L!f *h# followin« factors dictates a selection of alternate sequences? (check all that apply)
_I Order size _J. other: J. Capacity availability Other:
VI. CAPACITY UTILIZATION
A* III"*?1 Pefcent of your plant's work centers do you generate a load profile or load information? (check one)
_Q. Less than 25# Between 51 and 75# -1 Between 25 and 50# Over 75#
B* y°u sonetimes change customers' delivery dates in 162 order to improve capacity utilization?
Y e s SL No VII. BACKLOG
A. Do you use a measure of your plant's back in, .. . planning tool? P 8 Dack l 0 s a s a capacity
k. Yes OL NO
based^n^our'backlog?8dbUklll thSt^lyr® °ade
1. Capacity expansion decisions Increase in workforce
1_ Authorizing overtime Planning vacations
— Authorizing subcontract work J_ Other:
J_ Reduction of workforce J_ other: "
1_ Transfer employees between ~ departments
VIII. MANUFACTURING EFFECTIVENESS
A' delivery0dat«a? Uh'.ck"™)" y 0 U r C ° W B e e t %
40 teas than 40* of the time Between 81 and 65*
42 Between 40 and 55* fls Between 86 and 90*
62 Between % and ?0* 23 Between 91 and 95*
Z5 Between 71 and 80$ 22 Over 95$
What percent of the time are your company's actual times shorter than those of your competitors? (check one)
25 Lees than 25$ of the time QQ Between 76 and 85$
25 Between 25 and 45* 22 Between 86 and 95* 55 Between if6 and 65$ 2Z over 95$ ZQ Between 66 and 75$
7? e®8 than 5* Between 26 and 35$ 10 Between 5 and 15$ ££ Over 35$ 2Q Between 16 and 25$
S?£EI ^ Jj Less than 5$ Between 26 and 35$ 1£ Between 5 and 15$ £2 over 35$ 2Q Between 16 and 25$
B.
D.
163
E. What percent of total direct labor hours were overtime hours last year? (check one)
__5 Less than 5# of total direct hours 29 Between 26 and 35#
1Q Between 5 and 15# 2 0 Between 36 and 45#
2Q Between 16 and 25# Z£ Over 45#
F. What percent of total direct labor hours currently. are overtime hours? (check one)
_5 Less than 5# of total direct hours 2Q Between 26 and 35$
10 Between 5 and 15# £0 Between 36 and 45#
2Q Between 16 and 25# 22L Over if5#
G. Please estimate your company's overall direct labor productivity or efficiency. (Direct labor productivity is defined as: TOTAL STANDARD TIME or OUT PUT (at STANDARD)
TOTAL ACTUAL TIME ACTUALHOURS
If information of this kind is not readily available from routine reports, work sampling or other sources, please use your judgment.)(check one)
%
5Q, Less than 50# productivity Q2. Between 86 and 90#
5Z Between 50 and 65# Between 91 and 95#
20. Between 66 and 75# 92. Over 95# QQ, Between 76 and 85#
H. On the average, how many 8 hour shifts per week does your plant operate? (round to the nearest whole number)
21 Less than 5 shifts 10. 10 shifts
_1 5 shifts Between 11 and 11* shifts
6 Between 6 and 7 shifts 1J§. 15 shifts
j£. Between 8 and 9 shifts I.&. More than 15 shifts
I. "That percent of the total inventory value is dedicated to work in process inventory? (Total Inventory=Raw material inventory + Work in process inventory • Finished goods inventory.) (check one)
1 5 Less than 15# of total inventory 52 Between 46 and 60#
22 between 15 and 30# £& Between 61 and 75#
38 Between 31 aad 45# fiZ Over 75#
16if
IX. CLASSIFICATION DATA
A. Please indicate the number of employees at your location.
_1 500-1000 ]±_ 2001-2500
_2 1001-1500 Over 2500
1501-2000
B. Please choose from the list below a two-digit SIC (Stan-dard Industrial Code) that will best describe your com-pany's major product/s. (chooce only one code)
List of two-digit Standard Industrial Codes (SIC)
20 FOOD AND KINDRED PRODUCTS 21 TOBACCO MANUFACTURERS 22 TEXTILE MILL PRODUCTS 25 APPAREL AND OTHER FINISHED PRODUCTS HADE FROM FABRICS AND
SIMILAR MATERIALS 2if LUMBER AND WOOD PRODUCTS, EXCEPT FURNITURE 25 FURNITURE AND FIXTURES 26 PAPER AND ALLIED PRODUCTS 27 PRINTING, PUBLISHING, AND ALLIED INDUSTRIES 28 CHEMICALS AND ALLIED PRODUCTS 29 PETROLEUM REFINING, AND RELATED INDUSTRIES 30 RUBBER AND MISCELLANEOUS PLASTICS PRODUCTS. 31 LEATHER AND LEATHER PRODUCTS 32 STONE, CLAY, GLASS, AND CONCRETE PRODUCTS 33 PRIMARY METAL INDUSTRIES jflt FABRICATED METAL PRODUCTS, EXCEPT MACHINERY AND TRANSPOR-
TATION EQUIPMENT 35 MACHINERY, EXCEPT ELECTRICAL 36 ELECTRICAL AND ELECTRONIC MACHINERY, EQUIPMENT, AIID SUPPLIES 37 TRANSPORTATION EQUIPMENT ' 38 MEASURING, ANALYZING AND CONTROLLING INSTRUMENTS; PHOTO-
GRAPHIC, MEDICAL AND OPTICAL GOODS; WATCHES AND CLOCKS 39 MISCELLANEOUS MANUFACTURING INDUSTRIES
V • Flease indicate your type of operation, (check one)
JL_ Manufacture to stock only
2. Manufacture to order only Manufacture to stock and to order
Please indicate your area of formal education. (check all that apply)
3usiness Administration (management, accounting, etc.). Engineering Otuer:
165
Please indicate your membership with professional associations, (check all that apply)
American Production and Inventory Control Society
Institute of Industrial Engineers
National Association of Purchasing Management
American Management Association
Society of Manufacturing Engineers
Other:
Other:
F. Are you aware of a certification program offered by your professional association?
Yes No
G. If your answer to F was yes, have you gained a certificate such as CPIM awarded by APICS?
__ No
Yes; if so specify the certificate and association:
K. Please indicate your title.
Thank you. All information will be held in confidence. A stamped addressed envelope is attached.
To receive the results of this survey, just print the address information below:
Name ' Title
Company Name
Address
City .Texas Zip Code
(Please make any comments below and return with questionnaire.)
APPENDIX E
VARIABLES AND THEIR CORRESPONDING QUESTIONS
166
Variable Questions
Intensity
1. Production standards I A, B
2. Priority determination I I A, B, C, D
3. Delivery dates determination I I I A,B
4. Material requirements planning IV A, B, C
5. Routing information V A, B
6. Capacity utilization VI A, B
7. Backlog measurement VI I A,B
Effectiveness
1. Delivery dates performance VII I A
2. Lead times VI I I B
3. Subcontract work VI I I D
4. Direct labor overtime VI I I F
5. Direct labor efficiency VI I I G
6. Plant and equipment uti1ization VI I I H
7. Work in process inventory VI I I I
A P P E N D I X F
167
QUESTIONNAIRE RESPONSE FREQUENCIES
SURVEY OF CAPACITY MANAGEMENT PRACTICE
I. PRODUCTION STANDARDS
A, What percent of your plant operations are covered by production time standards? (check one)
££} Less than 253 20 Between 51 and ?5tf
JL Between 25 and 50* 22 Over 75*
B. Which of the following techniques are used in your company to set production standards? (check all that apply)
Zl'Time study 22 Historical records
Standard data 2 0 Work sampling
2 2 Predetermined motion times 10 Other:.
II. PRIORITY DETERMINATION
A. What percent of customer orders are assigned a prioritv level/code? (check one)
68 Less than 25* lj£ Between 51 and 75*
J Z Between 25 And 50* 3J_ Over 75*
B. What type of priority system is utilized in your company? (check all that apply)
Dynamic-critical ratios >8 Other:.
26. Dynamic-order size Other:.
2 3 Static-customer size
C. Do you regularly change a priority level/code as market conditions dictate, after an order has been released to the shop?
5 2 Y e e 62 No
D« Who has the final authority in assigning a priority level/code? (check one)
12. Sales Dept. 21. Top management
Li Manufacturing Dept. Other:
52. Jointly by Sales Dept. and Mfg. Dept
III. DELIVERY DATES
A. In most cases, delivery dates are promised based on: (check one)
Customer request 26. Customer request subject to _5. Available capacity available capacity
,5 Other:
168
B. What percent of the time do you seek and obtain from your customers, a forecast or an early warning of their requirements to help you better meet their needs? (check one)
2fc5 Less than 25# Jjj. Between 51 and 75# 26 Between 25 and 50# ^ Over 75#
IV. MATERIAL REQUIREMENTS PLANNING
A. Does your company use a material requirements planning system, (MRP)? (check one)
2k JJ Currently implementing 2k No
B. Does your company's capacity planning system directly interface with its material requirements planning system. (MRP)? (check all that apply)
£L5 Yee 23 Do not have an MRP system
2Q No JU Do not have a capacity planning system
C. For what percent of your plant's products (as measured in dollars) do you have an accurate bill of materials? (check one)
Less than 25# JL2 Between 51 and 75# Between 25 and 50# Over 75#
V. ROUTING INFORMATION
A. For what percent of your plant's products/components, (as measured in dollars) do you have routing information or operations sequence? (check one)
Less than 25# _3 Between 51 and 75#
Between 25 and 50# S3 Over 75#
B. Are alternate sequences or alternate routing an integral part of your planning system?
£3 Yes No
C. Which of the following factors dictates a selection of alternate sequences? (check all that apply)
23 Order size other; £8 Capacity availability _Jj. Other
VI. CAPACITY UTILIZATION
A. For what percent of your plant's work centers do you generate a load profile or load information? (check one)
26 Less than 25# 13 Between 51 and 75#
12 Between 25 and 50# ££ Over 75#
169 B. Do you sometimes change customers' delivery dates in
order to improve capacity utilization?
2D *es 49 No
VII. BACKLOG
A. Do you use a measure of your plant's back log as a capacity planning tool? * J
22 Yes 22 No
B. If your answer to A was yes, what decisions are made based on your backlog? (check all that apply)
62 Capacity expansion decisions ££ Increase in workforce
25 Authorizing overtime 43 Planning vacations
46 Authorizing subcontract work £§ Other:
22 Reduction of workforce _3 Other:.
S2 Transfer employees between departments
VIII. MANUFACTURING EFFECTIVENESS
A. What percent of the time does your company meet promised delivery^dates? (check one)
_2 Less than 40# of the time 2Q Between 81 and 85#
Between If0 and 55# lit Between 86 and 90#
Between 56 and 70# Between 91 and 95#
13 Between 71 and 80# 45 Over 95#
B. What percent of the time are your company's actual lead times shorter than those of your competitors? (check one)
Less than 25# of the time 12 Between 76 and 85#
15 Between 25 and 45# 12 Between 86 and 95#
32 Between 46 and 65# _2 Over 95#
15 Between 66 and 75#
C. What percent of the total output, (in dollars) that you could normally produce internally has been subcontracted last year due to lack of capacity? (check one)
2k Less than 5# _1 Between 26 and 35#
l£ Between 5 and 15# _3 over 35# _5 Between 16 and 25#
D. What percent of total output, (in dollars) that you could normally produce internally is currently subcontracted due to lack of capacity? (check 6ne)
1Q4 Less than 5# J. Between 26 and 35#
J£ Between 5 and 15# Over 35#
.3 Between 16 and 25#
170
E. What percent of total direct labor hours were overtime hours last year? (check one) overtime
33 Less than 5% of total direct hours _J, Between 26 and 35% ££ Between 5 and 15% __Q Between 36 and 1*5# 19 Between 16 and 25% _g Over If5*
F. What percent of total direct labor hours currently. ar#» overtime hours? (check one)
58 Less than 5% of total direct hours ..2 Between 26 and 35% 5Q Between 5 and 15% Between 36 and 45%
Between 16 and 25% Over 45%
G. Please estimate your company's overall direct labor productivity or efficiency. (Direct labor productivity is defined as: TOTAL STANDARD TIME or 0UTPUT(at swimiwirt
.TOTAL ACTUAL TIME ACTUAL HOURS ^
If information of this kind is not readily available from routine reports, work sampling or other sources, please use your Judgment.)(check one)
Less than 50% productivity £1. Between 86 and 90%
Between 50 and 65% lit Between 91 and 95% 12, Between 66 and 75% 20. Over 95% 2Z Between 76 and 85%
3. On the average, how many 8 hour shifts per week does your plant operate? (round to the nearest whole number)
_SL Les« than 5 shifts 10 shifts
20. 5 shifts Between 11 and 14 shifts Between 6 and 7 shifts 15 shifts
-5- Between 8 and 9 shifts ZX More than 15 shifts
I. What percent of the total inventory value is dedicated to wor.< in process inventory? (Total Inventory=Raw material inventory + Work in process inventory + Finished goods inventory.) (check one)
j&Less than 15% of total inventory Between ko and 60% 32 between 15 and 30% 3_ Between 61 and 75% 19 Between 31 and 45% 23 Over 75%
171
IX. CLASSIFICATION DATA
A. Please indicate the number of employees at your location.
1J2] 500-1000 2001-2500
-3 1001-1500 _£ Over 2500
_3 1501-2000
B. Please choose from the list below a two-digit SIC (Stan-dard Industrial Code) that will best describe your com-pany's major product/s. (choooe only one code)
List of two-digit Standard Industrial Codes (SIC)
20 FOOD AND KINDRED PRODUCTS 2.1 TOBACCO MANUFACTURERS 22 TEXTILE MILL PRODUCTS 2 3 SIMILAR MATERIALS F I N I S H E D P R 0 D U C T S FROM FABRICS AND 24 LUMBER AND WOOD PRODUCTS, EXCEPT FURNITURE 25 FURNITURE AND FIXTURES 26 PAPER AND ALLIED PRODUCTS 27 PRINTING, PUBLISHING, AND ALLIED INDUSTRIES 28 CHEMICALS AND ALLIED PRODUCTS 29 PETROLEUM REFINING, AND RELATED INDUSTRIES 30 RUBBER AND MISCELLANEOUS PLASTICS PRODUCTS 31 LEATHER AND LEATHER PRODUCTS 32 STONE, CLAY, GLASS, AND CONCRETE PRODUCTS 33 PRIMARY METAL INDUSTRIES
'''' KTlSiwiPffiOT P R 0 M C T S- K C E M MACHINERY AHD T3AN3FCR-
35 MACHINERY, EXCEPT ELECTRICAL JJ aCIRICAL jjj) ELECTRONIC MACHINERY, EQUIPMENT, /"ID SUP^LI'S
37 TRANSPORTATION EQUIPMENT ^ ' ~ y SUF.LIaS 3 8 AN^ZING AND CONTROLLING INSTRUMENTS; PHOTO-
GRAPHIC, MEDICAL AND OPTICAL GOODS: WATCHES AND CLOCKS 39 MISCELLANEOUS MANUFACTURING INDUSTRIES
C. Flease* indicate your type of operation, (check one)
Manufacture to stock only
23L Manufacture to order only
QQ Manufacture to stock and to order
D. Please indicate your area of formal education, (check all that apply)
7A Business Administration (management, accounting, stc.). 65 Engineering 15 Otuer:
172
(check al^that a£J5iy)emberShip p r o f e c s i o n a l associations,
23 American Production and Inventory Control Society
21 Institute of Industrial Engineers
_Jl National Association of Purchasing Management
2S American Management Association
3L1 Society of Manufacturing Engineers
IB Other:
13 Other:
F. Are you aware of a certification program offered by your professional association?
&5 Yes No
G. If your answer to F was yes, have you gained a certificate such as CPIM awarded by APICS?
5k No
_9 Yes; if so specify the certificate and "association:
K. Please indicate your title.
Thank you. All information will be held in confidence. A stamped addressed envelope is attached.
To receive the results of this survey, just print the address information below:
Name Title
Company Name ___________________
Address
City ,Texas Zip Code
(Please make any comments below and return with questionnaire.)
APPENDIX G
173
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TRANSFORMATION OF MATRICES
176
Fourteen-Var iab1e Analysis
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Effectiveness Variables Analysis
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TABLE 43
FACTOR SCORE COEFFICIENTS
177
Variable
Fourteen-Variable Analysis
Intensity Variables Analysis
F 2 | F 3
Production standards
Priority determlnation
Delivery dates determination
Material requirements planning
Routing information
Capacity utilization
Backlog measurement
Delivery dates performance
Lead times
Subcontract work
Direct labor overtime
Direct labor efficiency
Plant and equipment uti1ization
Work in process inv.
• 38
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. 12
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. 12
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.29
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.35
.51
.39
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.21
.50
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-.07
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J Ef fect i veness Variables Analysis
TT~r
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.38
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.34
.06
.48
, 0 6
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. 12
. 1 1
.43
.53
.21
,39
APPENDIX H
178
TABLE 44
EFFECTIVENESS MEAN SCORES CLASSIFIED BY AREA OF FORMAL EDUCATION
Variable Business Administration
Engineering
Delivery dates performance 88.80 86.67
Lead times 61.80 61. 16
Subcontract work 6.69 6. 19
Direct labor overtime 8.08 9.21
Direct labor efficiency 83.78 82.70
Plant and equipment uti1ization 9.65 9.52
Work in process inventory 36.73 33.89
Number of cases 78 63
179
TABLE 45
EFFECTIVENESS MEAN SCORES CLASSIFIED BY MEMBERSHIP WITH PROFESSIONAL ASSOCIATIONS
Variab1e SME AMA APICS I IE
Delivery dates performance 88.68 89.52 87.26 87. 19
Lead times 59.39 60.79 58.04 61.86
Subcontract work 5.00 8. 17 9.65 9. 14
Direct labor overtime 9.68 8. 10 8.91 10.00
Direct labor efficiency 82. 19 84. 14 84.09 78.71
Plant and equipment uti1ization 9. 16 10.86 8.83 9.43
Work in process inventory 27.61 38.24 36.30 34.71
Number of cases 31 29 23 21
Note: SME Society of Manufacturing Engineers, AMA -American Management Association, APICS - American Production and Inventory Control Society, I IE - Institute of Industrial Engineers.
180
TABLE 46
EFFECTIVENESS MEAN SCORES OF APICS MEMBERS CLASSIFIED BY THOSE WHO HOLD A CERTIFICATE
AND THOSE WHO DO NOT
Variable Members With A Certi f icate
Members Without A Certificate
Delivery dates performance 87.33 87.24
Lead times 51.67 60.29
Subcontract work 16. 17 7.35
Direct labor overtime 10.00 8.53
Direct labor efficiency 90.50 81.82
Plant and equipment uti1ization 9.67 8.53
Work in process inventory 43.33 33.80
Number of cases 6 17
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Dissertations
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Beuno-Neto, Pedro Rodrigues. "Aggregate Planning: Extensions and a Search-Regression Approach." Ph.D. diss., Stanford University, 1980.
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192
Fadamas, Nelson. "The Capacity Planning Problem: A Three
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Goodman, David Allen "A Modified Sectioning Search Approach
1972 Planning." Ph.D. diss., Yale University,
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McCormick, Marshall Blaine. "Aggregate Planning in the Make-to-Order Environment." Ph.D. diss., University of South Carolina, 1982.
Moghaddam, Jahanguir Moshtaghi. "A Study of the Factors
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Peterson, Rein "An Optimal Control Model for Smoothing
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Schneeberger, Hans-Martin. "Job Shop Scheduling in Pull Type Production Environment." Ph.D. diss., Purdue Uni-versity, 1984.
Shearon, Winston T., Jr. "A Study of the Aggregate Produc-tion Planning Problem." Ph.D. diss., University of Virginia, 1974.
Sikes, Thomas Wellington. "The Search Decision Rule Applied o Aggregate Planning: Improved Efficiency and Sto-
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193
Steinberg, Earle. "Sensitivity of Linear Decision Rule Cost Performance to State Variable Measurement Errors." Ph.D. diss., Georgia State University, 1976.
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Yuan, John Shia-Chang. "Algorithms and Mu1ti-Product Model in Production Scheduling and Employment Smoothing." Ph.D. diss., Stanford University, 1968.