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Systems Analysis and
Design
Sabitha S.
1
Systems Analysis
Systems analysis is the application
of the systems approach to
problem solving using computers.
The ingredients are systems
elements, processes and
technology.2
System
The term system is derived from
the Greek word systema, which
means an organized relationship
among functioning units or
components.
3
System
System is an orderly grouping of interdependent components linked together according to a
plan to achieve a specific objective.
4
Systems concept has three basic
implications:
1. A system must be designed to achieve a predetermined objective.
2. Interrelationships and interdependence must exist among the components.
3. The objectives of the organization as a whole have a higher priority than the objectives of its subsystems.
5
Information System
An information system can be any
organized combination of people,
hardware, software, communications
networks, and data resources that
stores and retrieves, transforms and
disseminates information in an
organization.
6
Characteristics of a System
1. Organization (Grouping)
2. Interaction
3. Interdependence
4. Integration
5. Central Objective
7
Elements of a System
1. Outputs
2. Inputs
3. Processor
4. Control
5. Feedback
6. Environment
7. Boundaries and interface
8
The Components of an
Information System
All information systems use people, hardware,
software, data and network resources to
perform input, processing, output, storage
and control activities that transform data
resources into information products.
9
The Components of an Information System
Network Resources
Control of System Performance
Storage of data Resources
Input
of
Data
Resources
Processing
Data
into
information
Output
of
information
Products
Network Resources
System Activities
10
The Components of an
Information System
All information systems use people, hardware,
software, data and network resources to
perform input, processing, output, storage
and control activities that transform data
resources into information products.
11
People Resources
People are the essential ingredient for the
successful operation of all information
systems. These people resources include
end users and IS specialists.
12
End users
End users also called users or clients are
people who use an information system or
the information it produces. They can be
customers, sales persons, engineers,
clerks, accountants or managers.
13
IS specialists
IS specialists are people who develop and operate
information systems. They include system
analysts, software developers, system operators
and other managerial, technical and clerical IS
personnel. System analysts design information
systems based on the information requirements
of end users, software developers create
computer programs based on the specifications of
system analysts, and system operators help to
monitor and operate large computer systems and
networks.
14
Hardware Resources
The concept of hardware resources includes all
physical devices and materials used in
information processing. It includes not only
machines such as computers and other
equipments, but also all the data media,
that is tangible objects on which data are
recorded, from sheets of paper to magnetic
disks.
15
Software Resources
The concept of software resources
includes all sets of information
processing instructions. It includes
programs and procedures (operating
instructions for the people who will use
an information system).
16
Data Resources
Data resources include text, image, video,
audio and other forms of data.
17
Network Resources
Telecommunications technologies and networks like the internet, intranets and extranets are
essential to the successful electronic business and commerce operations of all types of organizations and their computer-
based information systems. Telecommunications network consist of
computers, communications processors and other devices interconnected by
communications media and controlled by communications software.
18
Information System
Activities
1. Input data resources
2. Processing of data into information
3. Output of information products
4. Storage of data resources
5. Control of system performance
19
System Development Life Cycle
(SDLC)Recognition
of need
Feasibility
Study
Analysis
Design
Implementation
Post-implementation
& Maintenance20
Recognition of need/Requirement
determination
Preliminary Survey/ Initial
Investigation
21
Recognition of need/Requirement
determination
It involves studying the current business
system to find out how it works and
where improvements should be made.
System studies result in an evaluation of
how current methods are working and
whether adjustments are necessary or
possible.
22
Activities in Requirement
determination
1. Requirements anticipation
2. Requirements investigation
3. Requirements specification
23
Requirements anticipation
Foreseeing systems characteristics
based on previous experience.24
24
Requirements investigation
Study and documentation of the current
system using fact finding
techniques, data flow analysis, etc.
Using a variety of tools and
skills, analysts study the current
system and document its features for
further analysis.
25
Requirements specifications
The data produced during the fact-finding
investigation are analyzed to
determine requirements
specifications, the description of
features for a new system.
26
Requirements specifications
This activity has three inter related parts:
a. Analysis of factual data
b. Identification of essential requirements
c. Selection of requirements fulfillment
strategies.
27
Basic Requirements
Analysts structure their investigation by
seeking answers to four major
questions:
1. What is the basic business process?
2. What data are used or produced during
that process?
28
Basic Requirements
Analysts structure their investigation by
seeking answers to four major
questions:
3. What are the limits forced by time and
the volume of work?
4. What performance controls are used?
29
1. Understand the process
Analysts must raise questions like:
• What is the purpose of this business activity?
• What steps are performed?
• Where are they performed?
• Who performs them?
• How long does this take?
• How often it is done?
• Who uses the resulting information?
30
2. Identify data used and
information produced.
Analysts need to find out what data are
used to perform each activity.
31
3. Determine process timing and
volume
• Analysts should learn how often the
activities are repeated.
• Time required for performing an
activity also has to be considered.
32
4. Identify controls
The analysts can examine whether weak or
missing controls are there.
• Are there specific performance
standards?
• Who compares performance against
standards?
• How are mistakes caught?
• How are errors handled?33
Questions to answer in developing
a system profile
Volume
• What volume of activity occurs?
• How frequently does the activity occur?
• Does the activity occur according to any
cycle?
34
Questions to answer in developing
a system profile
Control
• What areas need specific control?
• What control methods are currently used?
• What yardsticks are used to measure and
assess performance?
• Are specific security precautions taken to
safeguard against improper activity?
35
Questions to answer in developing
a system profile
Processes
• What separate processes, steps or
functions make up the activity?
• What triggers (generate) the activity?
• How long does each activity take? What
factors govern the amount of time taken?
• What delays can occur?
36
Questions to answer in developing
a system profile
Processes
• How does interaction with elements
occur?
• What is the cost of system operation?
• Are there specific management
objectives to be satisfied?
37
Questions to answer in developing
a system profile
Data
• What data enter the system and what is
the origin of the data?
• In what form are the system data
received? Stored?
• Which data items are stored in the
system or as part of the activities of the
system?38
Questions to answer in developing
a system profile
Data
• Who uses the information produced by
the system? What is it used for?
• What is not used? (irrelevant parts)
• What data are often missing?
• Are any data developed or used in an ad
hoc basis?
39
Strategies for determining
Information Requirements
1. Asking
2. Getting information from the
existing information system
3. Prototyping
40
Information Gathering Tools
1. Review of literature, procedures
and forms
2. Onsite observation
3. Interviews
4. Questionnaires
41
Structured Analysis
Structured Analysis is a set of techniques and graphical tools that allow the analyst to develop a new kind of system specifications that are easily understandable to the user.
42
Tools of Structured Analysis
1. Data Flow Diagram
2. Data Dictionary
3. Decision Tree
4. Structured English
5. Decision Tables
43
Data Flow Diagram (DFD)
A DFD is the graphic representation of data
movement, processes, and files (data
stores) used in support of an information
system.
It has the purpose of clarifying system
requirements and identifying major
transformations.44
Example
Draw the DFD for a system which takes
orders from the customer (book store,
library, etc.), checks them against an
index the books available, verifies
customer credit through a credit
information file, and authorizes
shipment with an invoice.
45
DFD
CUSTOMER Process OrderCUSTOMER
INFORMATION FILE
BOOK
INFORMATION FILE
Orders
Invoice
Credit
check
46
Data Dictionary
A Data Dictionary is a structured
repository of data about data such
as meaning, relationships to other
data, origin, usage, and format.
47
Decision Tree
It is a graphic representation of conditions
and outcomes resembling the
branches of a tree. It is easy to
construct, understand and interpret.
It simply sketches the logical structure
based on the stated policy.
48
Example
Consider the discount policy of the publisher.
For any purchase of 5 or fewer copies per book title, no discount is allowed.
Otherwise,
Bookstores get a trade discount of 25%; for orders from libraries and individuals, 5%
allowed on orders of 6-19 copies per book title; 10% on orders for 20-49 copies per book title; 15% on orders for 50 copies or
more per book title.
49
Decision Tree for Discount Policy
Discount
Policy
Bookstore
Individual
6 or more
Less than 6
50 or more
20-49
6-19
Less than 6
25%
Nil
15%
10%
5%
Nil
Discount
Policy
Bookstore
Individual
6 or more
Less than 6
50 or more
20-49
6-19
Less than 6
25%
Nil
15%
10%
5%
Nil
50
Structured English
Structured English is strongly worded formal English statements used for
communicating processing rules or describing the structure of a system.
Structured English borrows heavily from structured programming. Thus structured
English aims at getting the benefits of both the programming logic and natural
language. 51
Structured English
Structured English consists of the following elements:
1. Operation statements written as English phrases executed from the top down
2. Conditional blocks indicated by keywords such as IF, THEN, and ELSE
3. Repetition blocks indicated by keywords such as DO, WHILE, and UNTIL
52
Example
IF customer has a Bank Account THEN
IF Customer has no dues from previous account THEN
Allow loan facility
ELSE
IF Management Approval is obtained THEN
Allow loan facility
ELSE
Reject
ENDIF
ENDIF
ELSE
Reject
ENDIF 53
Decision Table
A decision table is a table of
contingencies for defining a problem
and the actions to be taken. It is a
single representation of the
relationships between conditions and
actions.
54
Decision Table
A Decision Table consists of two parts: stub and entry.
The stub part is divided into an upper quadrant called the condition stub and a
lower quadrant called the action stub.
The entry part is also divided into an upper quadrant called the condition entry and a lower quadrant called the action entry.
55
Decision Table for Discount Policy
Customer is bookstore?
Order-size 6 copies or more?
IF Customer Librarian or Individual?
(condition) Order-size 50 copies or more?
Order-size 20-49 copies?
Order-size 6-19 copies?
Allow 25% discount
Allow 15% discount
THEN Allow 10% discount
(action) Allow 5% discount
No discount allowed
Y Y N N N N
Y N N N N N
Y Y Y Y
Y N N N
Y N N
Y N
X
X
X
X
X X
Condition StubCondition Entry
Action Stub Action Entry
1 2 3 4 5 6
56
Feasibility Study
A Feasibility study is to serve as a decision document, it must answer three key questions:
1. Is there a new and better way to do the job that will benefit the user?
2. What are the costs and savings of the alternatives?
3. What is recommended?57
Feasibility Considerations
Three key considerations are involved in the feasibility analysis.
• Economic Feasibility
• Technical Feasibility
• Behavioral Feasibility
58
Economic Feasibility Cost/Benefit Analysis
It is the most frequently used
method for evaluating the
effectiveness of the system.
59
Economic feasibilityCost/Benefit Analysis
Identifying the advantages or benefits
and the disadvantages or costs of a
proposed solution.
60
Economic Feasibility Cost/Benefit Analysis
The procedure is to determine the benefits and savings that are expected from a candidate system and compare them with costs. If benefits outweigh costs, then the decision is made to design and implement the system. Otherwise further justification and alterations in the proposed system will have to be made if it is to have a chance of to be implemented.
61
Cost/Benefit Analysis
Identifying the advantages or benefits
and the disadvantages or costs of a
proposed solution.
62
Technical Feasibility
It centers around the existing
computer system and to what
extent it can support the
proposed addition.
63
Behavioral Feasibility
User friendliness of the
proposed system.
64
Steps in Feasibility Analysis
1. Form a project team and appoint a project leader.
2. Prepare system flowcharts.
3. Enumerate potential candidate systems.
4. Describe and identify characteristics of candidate systems.
65
Steps in Feasibility Analysis
5. Determine and evaluate
performance and cost
effectiveness of each candidate
system.
66
Performance/Cost factors
Performance CostsSystem accuracy System development
Growth potential User Training
Response time System operations
User-friendly Payback
67
Steps in Feasibility Analysis
6. Weight system performance and cost data.
7. Select the best candidate system.
8. Prepare and report final project directive to management.
68
System Analysis
Detailed evaluation of present
system.
Data collection
69
System Analysis
Systems Analysis is not a preliminary
study. It is an in-depth study of end
user information needs that produces
functional requirements that are used
as the basis for the design of a new
information system.
70
System Analysis
Systems Analysis traditionally involves a detailed study of:
1. The information needs of a company and end users.
2. The activities, resources and products of one or more of the present information systems being used.
3. The information system capabilities required to meet the information requirements of the organization and those of other business stakeholders that may use the system.
71
Categories of System Analysis
1. Organizational Analysis
2. Analysis of the Present System
3. Functional Requirements Analysis
72
System Design
Output Design
Input Design
File /Database Design
Procedure Design
73
Objectives of Information
System Design
1. Specify logical design elements
2. Support business activities
3. Meet User requirements
4. Easy to use
5. Provide software specifications
6. Conform to design standards
74
1. Specify logical design
elements
System design involves first logical
design and then physical construction
of the system. When analysts
formulate a logical design, they write
the detailed specifications for the new
system. They describe its features
such as the outputs, inputs,
databases, procedures, etc.
contd…75
1. Specify logical design
elements
The statement of these features is
termed as the design specifications of
the system.
76
2. Support Business Activities
The fundamental objective in the design
of an information system is to ensure
that it supports the business activity
for which it is developed.
Contd…
77
2. Support Business Activities
For example, if it is essential for an
organization to move information very
quickly to remain competitive, then
the design specifications of the
information system must be based
around this essential business
objective.
78
3. Ensure that system features
meet user requirements
User requirements are translated into
system characteristics during design. We
say that an information system meets
user needs if it accomplishes the
following:
• Performs the right procedures properly.
• Presents information and instructions in
an acceptable and effective fashion.
Contd…79
3. Ensure that system features
meet user requirements
• Produces accurate results
• Provides an acceptable interface and
method of interaction
• Is perceived by users as a reliable
system.
80
4. Provide a system engineered
for ease of use by people
• Favorable human engineering
• Ergonomic design that is physically
comfortable and contributes to user
effectiveness and efficiency.
81
5. Provide software specifications
System design includes formulating
software specifications.
82
6. Conform to design standards
System design specifications are
established within the systems
development standards such as data
standards and structural standards.
83
Elements of the Design
Analysts must design the following elements:
• Data flows
• Data stores
• Processes
• Procedures
• Controls
• Roles84
Data Flows
The movement of data into, around
and out of the system.
85
Data Stores
Temporary or permanent collections
of data.
86
Processes
Activities to accept, manipulate and
deliver data and information.
87
Procedures
Methods and routines for using the
information system to achieve the
intended results.
88
Controls
Standards and guidelines for
determining whether activities are
occurring in the anticipated or
accepted manner, that is ‘under
control’. Also specify actions to
take when problems or unexpected
circumstances are detected.
89
Roles
The responsibilities of all persons
involved in the new system
including end users, computer
operators and support personnel.
90
System Design – Features to be
designed
a. Design of output
b. Design of files
c. Design of database interactions
d. Design of input
e. Design of control
f. Design of procedures
g. Design of program specifications
91
Input Design
Systems analysts decide the following
input design details:
1. What data to input
2. What medium to use
3. How the data should be arranged
4. The dialogue to guide users in
providing input
Contd… 92
Input Design
Systems analysts decide the following
input design details:
5. Data items and transactions
needing validation to detect
errors.
6. Methods for performing input
validation and steps to follow
when errors occur.93
Objectives of Input Design
1. Controlling the amount of input
2. Avoiding delay
3. Avoiding errors in data
4. Avoiding extra steps
5. Keeping the process simple
94
Output Design
When designing the output, the system
analysts must accomplish the
following:
1. Determine what information to
present
2. Decide whether to display, print
or speak the information and
select the output medium. Contd…95
Output Design
3. Arrange the presentation of
information in an acceptable
format.
4. Decide how to distribute the
output to intended recipients.
96
Output Objectives
1. Convey information about past
activities, current status or
projections of the future.
2. Signal important
events, opportunities, problems or
warnings.
3. Trigger an action
4. Confirm an action.97
Key Output questions
1. Who will receive the output
2. What is its planned use?
3. How much detail is needed?
4. When and how often the output
needed?
5. By what method? (printed or
displayed)
98
File Design
The decisions to be made during file design are:
1. Which data items to include in a record
format within the file.
2. Length of each record based on the
characteristics of the data items on
which it is based.
3. The sequencing of records within the
file.
99
BASIC FILE TERMINOLOGY
Data Item
Record
Record Key
Entity
File
Databases
100
Entity
An entity is any person, place, thing
or event of interest to the
organization and about which
data are captured, stored or
processed.
101
File Organizations
1. Sequential Organization
2. Indexed-Sequential Organization
3. Inverted List Organization
4. Direct Access Organization
102
System Testing
Unit Testing
Combined Module Testing
User Acceptance Testing
103
System Testing
The first test of a system is to see whether it
produces the correct outputs. Following this
step, a variety of other tests are conducted:
• Online response
• Volume
• Stress testing
• Recovery and security
• Usability 104
System Implementation
User Training
Site Preparation
File / System Conversion
Parallel Run
User-friendly documentation
105
Evaluating Hardware, Software and Services
For evaluating the hardware and
software, large companies may require
suppliers to present bids and proposals
based on system specifications
developed during the design stage of
systems development. Minimum
acceptable physical and performance
characteristics for all hardware and
software requirements are established.
106
Quality Assurance
Methods for ensuring that
information systems are free
from errors and fraud and
provide information products of
high quality.
107
Levels of Quality Assurance
There are three levels of quality assurance:
1. Testing
2. Validation and
3. Certification
108
Documentation
A collection of documents or information
that describes a computer
program, information system or
required data processing operations.
Examples : Sample Data Entry Display
screens, forms and reports.
109
Documentation
Documentation is extremely important in
diagnosing errors and making
changes, especially if the end users or
systems analysts who developed a
system are no longer with the
organization.
110
Documentation
Documentation serves as a method of communication among the people
responsible for developing, implementing and
maintaining a computer based system. Installing and operating a newly
designed system or modifying an established application requires a
detailed record of that system’s design.
111
Training
Training is a vital implementation activity.
Training may involve activities like data
entry, or it may also involve all aspects
of the proper use of a new system.
112
Training
Managers and end users must be educated
in how the new technology impacts the
company’s business operations and
management. This knowledge should
be supplemented by training
programmes for any new hardware
devices, software packages and their
use for specific work activities.
113
Training Aids
1. The user manual
2. Help screens
3. Data dictionary
4. Job performance aids
Eg: Flowcharts to guide the user in
detecting and handling errors, restarting
system, etc.
114
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