effective project management: traditional, agile, extreme

Effective Project Management: Traditional, Agile, Extreme

Presented by(facilitator name)

Managing Complexity in the Face of Uncertainty

Ch04: How to Plan a Project

The Importance of Planning Using application software packages to plan projects Planning & conducting the Joint Project Planning Session (JPPS) Writing a Project Description Statement Building the Work Breakdown Structure (WBS) Estimating task duration Estimating resource requirements Estimating cost Constructing the project network diagram Analyzing the project network diagram Leveling resources Writing work packages Writing an effective project proposal

Summary of Chapter 4


Figure04-01

The Pain Curve

GoodPlanning

PoorPlanning

Pain

Time18-36%


Planning Reduces Uncertainty: consider the likely outcomes and to put the necessary corrective measures in place when things don’t happen according to plan.

Planning Increases Understanding: better understanding of the goals and objectives of the project

Planning Improves Efficiency: take advantage of resource availability (schedule work in parallel)

The Importance of Planning


Yes Very large projects Distributed teams Extensive use of vendors and contractors

No Small projects Short duration project increments Adds too much non-value-added work Frequent scope and requirements changes

Using Software Packages to Plan a Project


Sticky notes (assorted colors) Marking pens (assorted colors) Plenty of whiteboard space

Project Planning Tools


Task ID Unique task name Task duration Task labor Resource requirements Task manager ES, EF, LS, and LF (calculated values) Critical Path (calculated)

Uses for Sticky Notes


Uses for Sticky Notes…

Color-coded sticky notes offer a number of alternatives for the creative planner. For example, you can use a different color to represent each of the following:

The type of task (critical, for example)

Specific parts of the WBS (design, build, test, and implement, for example)

A position on the team (a critical or scarce skill, for example)

Define dependency relationships Identify the critical path

Uses for Marking Pens


Project Overview Statement Work Breakdown Structure Dependency Diagram Initial Project Schedule Final Project Schedule Resource Schedule Issues Log Updated Project Schedule

Uses for the Whiteboard


Very small projects < ½ day Small projects < 1 day Medium projects 2 days Large projects 3-4 days Very large projects ???

How Much Time Should Planning Take?


Planning team reviews POS for clarity Planning team creates the complete WBS Estimate task duration and resource needs Construct project network diagram Determine critical path Revise and approve project completion date Finalize resource schedule Gain consensus on the project plan

How to Run a Project Planning Session


Planning and Conducting Joint Project PlanningSessions

The JPPS is a group session in which all of the people who are involved in the project meet to develop the detailed plan.

The session can last from one to three days, and it can be work-intensive.

Objective: Develop a project plan that meets the COS as negotiated between the requestor and the provider, and as described in the POS.

Simple? No

Why? The client and the project team are generally impatient to get on with

the work of the project. Team members don’t have time for planning — there is too much work

to do and too many clients to satisfy.

Planning the JPPS

Team planning has always been viewed as advantageous over other forms of project planning, such as the project manager planning the project by walking around gathering data for the plan.

The first document considered in the JPPS is the POS.

The project team might write the Project Definition Statement (PDS) — their understanding of the project.

The PDS is nothing more than an expanded version of the POS, but from the perspective of the planning team.

Attendees Facilities Equipment Agenda Deliverables Project Proposal

The Planning Meeting Components


Attendees

The JPPS participants are invited from among those who might be affected by or have input into the project.

If the project involves deliverables or is a new process or procedure, then anyone who has input to the process, receives output from the process, or handles the deliverables should be invited to participate in the JPPS.

Facilitator: not have an interest or bring biases Project manager: concentrate on the plan itself Another project manager: facilitator JPP consultant: another source of qualified JPPS facilitators Technographer: expert in the software tools used to document the

project plan Core project team: individuals (from the client and from the provider) who will

stay with the project from the first day to the last day. Client representative: contribute to resolutions of change requests. Resource managers Project champion : drives the project and sells it to senior management

The Planning Meeting Attendees


The Planning Meeting Attendees

Functional managers: manage areas that can either provide input to or receive output from the project deliverables

Process owner: If the project deliverables do not smoothly integrate into their processes, either the project plan or the affected processes will have to be altered.

Facilities Comfortable Away from interruptions (off-site or on-site) Break-out rooms?

Equipment Break-out group work areas (table, chairs, bflip charts) Whiteboards Projection equipment

The Planning Session Facilities & Equipment


Session #1 Negotiate the COS or generate the RBS

Session #2 Write the POS

Session #3 Part 1: Planning Kick-off Part 2: Working session

The Complete Planning Agenda


Session #3 (JPPS)…

1. The entire planning team creates the first-level WBS.2. Subject matter experts develop further decomposition,

with the entire planning team observing and commenting.

3. Estimate activity durations and resource requirements.4. Construct a project network diagram.5. Determine the critical path.6. Revise and approve the project completion date.7. Finalize the resource schedule.8. Gain consensus on the project plan.

Deliverables

The deliverables from the JPPS are:

Work Breakdown Structure

Activity Duration Estimates

Resource Requirements

Project Network Schedule

Activity Schedule

Resource Assignments

Project Notebook

The Work Breakdown Structure (WBS) is a hierarchical description of all of the work that must be done to meet the needs of the client.

Definition of the WBS


The Requirements Breakdown Structure (RBS) is the input to the WBS construction process.

Hierarchical visualization of the WBS

Figure04-02


WBS…

Terms An activity is simply a chunk of work.

A task is a smaller chunk of work.

An activity is composed of two or ore tasks.

When the tasks that make up an activity are complete, the activity is complete.

A work package is a complete description of how the tasks that make up an activity will actually be done. It includes a description of the what, who, when, and how of the work.

WBS terms…

Breaking down work into a hierarchy of activities, tasks, and work packages is called decomposition.

Decomposition is important to the overall project plan because it enables you to estimate the duration of the project, determine the required resources, and schedule the work.

Thought process tool: It helps the project manager and the planning team visualize exactly how the work of the project can be defined and managed effectively.

Architectural design tool: WBS is a picture of the work of the project and how the items of work are related to one another.

Planning tool: It is at the lowest activity level of the WBS that you will estimate effort, elapsed time, and resource requirements; build a schedule of when the work will be completed; and estimate deliverable dates and project completion.

Project status reporting tool: Shading is often used to highlight completed tasks and activities. the WBS defines milestone events that can be reported to senior management and the client.

Why is the WBS Important?


Top-Down Approach Team Approach Subteam Approach

Bottom-Up Approach

Which is best?When?Why?

How to Build a WBS


Top-Down Approach

A sufficient level of detail to enable you to estimate time, cost, and resource requirements first at the activity level and then aggregate to the project level.

Many activities should be performed in parallel, rather than in sequence.

Two variations of the top-down approach: Team Approach: need longer time but is the better Subteam Approach: divide the planning team into as many

subteams as there are activities at Level 1 of the WBS. the entire planning team decides on the approach for the first-level breakdown. After that, the group is partitioned into subteams, with each subteam having some expertise for that part of the WBS.

Bottom-Up Approach

This approach is more like a brainstorming session than an organized approach to building the WBS.

The first steps in the bottom-up approach are the same as those for the top-down approach. Namely, the entire planning team agrees to the first-level breakdown.

The planning team is then divided into as many groups as there are first-level activities.

Each group makes a list of the activities that must be accomplished in order to complete the first-level activity.

Which is best?

The bottom-up approach randomly identifies activities and tasks, which increases the possibility of missing something.

On the other hand, the top-down approach is a logically

organized approach, and the likelihood of missing an activity or task is minimal.

The author recommend the top-down approach

Using the WBS for Large Projects

As project size increases, it becomes unwieldy to build the entire WBS with the all of the planning team assembled.

Begin by decomposing the WBS down to Level 3

At that point, develop intermediate estimates of time, resources, and dependencies for all Level 3 activities.

The planning session is adjourned, and the Level 3 activity managers are charged with completing the WBS for their part of the project.

Then the full JPPS team can be reassembled, and the planning process continues from that point.

Status and completion are measurable Can I determine activity status at any point in time?

The activity is bounded. Is there a defined start and end event?

The activity has a deliverable. Does the activity have a deliverable?

Time and cost are easily estimated. Can I easily estimate time and cost?

Activity duration is within acceptable limits. Is the activity duration within acceptable limits?

Work assignments are independent. Can the activity work be done without interruption?

WBS Completion Criteria


WBS Completion Criteria…

If the activity does not possess all six of these characteristics, decompose the activity and check it again at that next lower level of decomposition.

As soon as an activity possesses the six characteristics, there is no need to further decompose it.

Status and Completion Are Measurable

What has been actually completed (that is approved) and what remains to be done, along with an estimate to completion.

A simple metric that has met with some success is to compute the proportion of tasks completed as a percentage of all tasks that make up the activity. For example, if the activity has six tasks associated with it and

four of the tasks are complete, the ratio of tasks completed to total tasks is 4/6 — that is, the activity is 60 percent complete. Even if work is done on the fifth task in this activity, because the task is not complete on the report date, it cannot be counted in the ratio.

The Activity Is Bounded

Each activity should have a clearly defined start and end event.

After the start event has occurred, work can begin on the activity.

The deliverable is most likely associated with the end event that signals work is closed on the activity.

The Activity Has a Deliverable

The deliverable is a visible sign that the activity is complete.

This sign could be an approving manager’s signature, a physical product or document, the authorization to proceed to the next activity, or some other sign of completion.

The deliverable from an activity is output from that activity, which then becomes input to one or more other activities that follow its completion.

Time and Cost Are Easily Estimated

Estimating time and cost at the lowest level of decomposition in the WBS enables you to aggregate to higher levels and estimate the total project cost and the completion date.

Activity Duration Is Within Acceptable Limits

The author recommend that an activity have a duration of less than two calendar weeks.

Work Assignments Are Independent

An activity should continue reasonably well without interruption and without the need for additional input or information until the activity is complete.

The work effort could be contiguous, but it can be scheduled otherwise for a variety of reasons. You can choose to schedule it in parts because of resource availability, but you could have scheduled it as one continuous stream of work.

The client didn’t participate in building the WBS like you expected.

You have an uncomfortable feeling Scope change is likely to be a big part of the project Choose a PMLC model that accommodates frequent

change

WBS Completion Criteria – The 7th criterion


Stopping Before Completion Criteria Are Met Decomposing Beyond Completion of the Criteria

Short duration projects High risk activities Large duration variance

WBS Completion Criteria – Exceptions


RBS is a subset of the WBS

Figure04-03

Project goaland solution

Requirement 1

Function1.1

Feature1.2.1.1

Featuren.3.1

Sub-function1.2.3

Requirement n

Function1.2

Function1.3

Functionn.1

Functionn.2

Functionn.3

Sub-function1.2.2

Sub-function1.2.1

Featuren.3.2

Featuren.3.3

Featuren.3.4

Feature1.2.1.2

Feature1.2.1.3

Feature1.2.1.4

Activity1.2.1.1.1

Task1.2.1.1.3.3

Activity1.2.1.1.2

Activity1.2.1.1.3

Task1.2.1.1.3.2

Task1.2.1.1.3.1

Activityn.3.4.1

Taskn.3.4.3.3

Activityn.3.4.2

Activityn.3.4.3

Taskn.3.4.3.2

Taskn.3.4.3.1

RBS WBS


Noun-type Approaches Physical components Functional components

Verb-type Approaches Design-build-test-implement Objectives

Organizational approaches Geographic Departmental Business process

Which is best?When?Why?

Approaches to Building the WBS


Noun-type Approaches: Noun-type Approaches: defines the deliverable of the project in terms of the

components:components: Physical components Functional components

Currently recommended by PMI. Closed to the RBS. RBS is a part of the WBS




Building the WBS

RBS is a subset of the WBS

Figure04-03

Project goaland solution

Requirement 1

Function1.1

Feature1.2.1.1

Featuren.3.1

Sub-function1.2.3

Requirement n

Function1.2

Function1.3

Functionn.1

Functionn.2

Functionn.3

Sub-function1.2.2

Sub-function1.2.1

Featuren.3.2

Featuren.3.3

Featuren.3.4

Feature1.2.1.2

Feature1.2.1.3

Feature1.2.1.4

Activity1.2.1.1.1

Task1.2.1.1.3.3

Activity1.2.1.1.2

Activity1.2.1.1.3

Task1.2.1.1.3.2

Task1.2.1.1.3.1

Activityn.3.4.1

Taskn.3.4.3.3

Activityn.3.4.2

Activityn.3.4.3

Taskn.3.4.3.2

Taskn.3.4.3.1

RBS WBS


RBSRBS: what must be done

WBSWBS: How it will be done



Verb-type ApproachesVerb-type Approaches

Define the deliverable of the project in terms of action action that must be done to produce the deliverable.

Design-build-test-implement used in projects that involve methodology such as system development

Objectives: used when frequent progress reports submitted to the senior management.Objectives are almost always related to business value and will be well received by senior management as well as the client.Cause some difficulty because objectives always overlap.



Organizational approachesOrganizational approaches

Used only when forced by senior management and organizational structureTypes include:

GeographicDepartmentalBusiness process

Organizational approaches: Organizational approaches: Geographic

If project work is geographically dispersed, it may make sense from coordination and communication perspectives to partition the work first by geographic location and then by some other approach at each location.

Organizational approaches: Organizational approaches: Departmental

you might benefit from partitioning the project first by department and then within each department by whatever approach makes sense.

You benefit from this structure in that a major portion of the project work is under the organizational control of a single manager, which in turn simplifies resource allocation.

Conversely, using this approach increases the need for communication and coordination across organizational boundaries.

Organizational approaches:Organizational approaches:

This approach involves breaking the project down first by business process and then by some other method for each process.

This has the same advantages and disadvantages as the departmental approach, with the added complication that integration of the deliverables from each process can be more difficult when you use this approach.

The difficulty arises from process interactions at the boundaries of the involved processes.

Graphical WBS for a House

HOUSE

SITE FOUNDATION FRAMING WALLS ROOFING UTILITIES LANDSCAPINGFINISHWORK

Layout Grade Excavate

ErectForms

PourConcrete

Removeforms

InstallSheathing

LayShingles

HangSheetrock

Tape& Bed ELECT. GAS WATER

DoRough-in

Work

DoRough-in

Work

DoRough-in

Work

GetBuildingInspect.

GetBuildingInspect.

GetBuildingInspect.

DoFinishWork

DoFinishWork

DoFinishWork

InstallCabinets

InstallAppliances

InstallFurnace

Lay

Carpet

PaintWalls &Molding

HangWallpaper

LayTile

FLOORJOISTS

SUB-FLOOR

STUDWALLS

FRAMEROOF

Install1st

Floor

Install1st

Floor

Install1st

Floor

Install2nd

Floor

Install2nd

Floor

Install2nd

Floor

Figure04-04


Indented Outline WBS for a House

1. SITE PREPARATION

1.1. Layout

1.2. Grading

1.3. Excavation

2. FOUNDATION

2.1. Erect Forms

2.2. Pour Concrete

2.3. Remove Forms

3. FRAMING

3.1. Floor Joists

3.1.1. Install first floor joists

3.1.2. Install second floor joists

3.2. Sub-flooring

3.2.1. Install first floor sub-flooring

3.2.2. Install second floor sub-flooring

3.3. Stud Walls

3.3.1. Erect first floor stud walls

3.3.2. Erect second floor stud walls

3.4. Frame the roof

Figure04-05


WBS for a Waterfall SDM

SYSTEMS DEVELOPMENT PROJECT

ImplementationDefinition Design

State objectives

Define requirements

Choose SDM

Get approval

Functional

Technical

Programming

Installation

Operation

Source code

JCL

Documentation

Get approval

Testing

Training

Cut-over

Operate system

Review

Audit

Get approval

Clarify request

Establish objectives

Identify key issues

Obtain current doc.

Define new reqmts

Identify interfaces

Design I/O

Confirm specs

Define pgm specs

Prepare system flow

Convert data

Build integration test plan

Get approval

Construct codeConduct unit test

Construct JCLConduct system test

Finalize test planCreate test dataConduct testConduct operations trainingConduct user training

Finalize planConvert dataCut-over to production

Establish planReview performance

Complete financial analysisAnalyze risks

Spec audits/controls

Get approval

Figure04-06


The durationduration of a project is the elapsed time in business working days or shifts, not including weekends, holidays, or other non-work days.

Work effort Work effort is labor required to complete a task

Duration and work effort are not the same thing

Example: PM course: Duration: one semester Work effort: 42 hrs

Time Estimation


Figure04-07

2

4

6

8

10

2 4 6 8 10 12 14 16 18 20

L = DLabor

Duration

L = .75D

33% unplanned interruptions

MODEL ASSUMPTIONS

* Individuals work at 75 percent efficiency rate.* Unplanned interruptions account for 33 percent of clock time.

Elapsed time (duration) versus work time (labor)


Estimate duration to build the schedule and determine when the project will be completed

Estimate labor when you have to contain expenses within a budget

Should I Estimate Task Duration or Task Labor?


1. Pick up the chair

2. Carry it to the door

3. Set the chair down

4. Open the door

5. Hold the door open with your foot as you pick up the chair

6. Carry the chair out the door

7. Set the chair in the hallway

Time

# of people on the team

1 2 3 4

Resource Loading vs. Task Duration


Adding more resources to hold a task’s duration within the planning limits can be effective. This is called ‘‘crashing the crashing the task”task”

The crash-pointcrash-point is thepoint where adding more resources will increase task duration

Time

# of people on the team

1 2 3 4



Considerations of adding new resources:Considerations of adding new resources:

The amount of reduction in duration that results from adding resources

The impact on risk that results from adding another resource.

Partitioning the task so that more than one resource can work on it simultaneously. For some tasks, this will be easy; for others it may be impossible.



Varying skill levels Unexpected events

e.g. Random acts of nature, vendor delays, incorrect shipments of materials, traffic jams, and power failures.

Efficiency of work time Some will be more affected by interruptions than others.

Mistakes and misunderstandings Variation within the capability of the system Common cause variation

duration is a random variable.

Causes of Variation in Duration


1. Extrapolating based on similarity to other activities.1. Extrapolating based on similarity to other activities.

2. Historical data2. Historical data Simple way: extract similar tasks from the database and

compute an average More complicated: use sophisticated regression models based

on full info. about characteristics of the task, the skill set of the people working on it, actual vs. planned duration and other variables.

3. Expert advice3. Expert advice e.g. when technology is being used for the first time in the

organization, consult outside experts. Vendors may be a good source, as are non-

competitors who use that technology

Six Simple Ways to Estimate Task Duration


4. Delphi techniqueDelphi technique The original versionThe original version

use a small panel of experts asked for their estimate independently of one another.

The results are tabulated and shared with the panel members, who are then asked to submit their own second and third estimate.

The modified versionThe modified version In the absence of experts, each individual in the

project group is asked to make his or her best guess of the task duration.

Participants whose estimates fall in the outer quartiles are asked to share the reason for their guess.

After listening to the arguments, each group member is asked to guess again, and so on.

Six Simple Ways to Estimate Task Duration


First Pass

Second Pass

Third Pass

The Delphi Technique

Figure04-08


Ways to Estimate Task Duration

O M PE

O: OptimisticP: PessimisticM: Most Likely

O + 4M + P6

E =

Figure04-09


5. The Three-Point Method5. The Three-Point Method

Ways to Estimate Task Duration


6. Applying the Wide-Band Delphi Technique6. Applying the Wide-Band Delphi Technique

Combining the Delphi and three-point methods

Members are asked, at each iteration, to give their optimistic, pessimistic, and most likely estimates for the duration of the chosen task.

Averages are computed for each of the three estimates

Estimates Have a Life Cycle Too

time

range

You will be smarter tomorrowthan you are today.

Figure04-10


Six techniques discussed previously can be used to estimate resources.

Resource types: People Facilities Equipment Money Materials

Tools used to schedule people: Skills matrices Skill categories Skill levels

Estimating Resource Requirements


Assigning Staff to Activities

Figure04-11


In the first (needs inventory) matrix, rows represent the activities and columns are the skills.

In the second (skills inventory) matrix, rows identify the staff and columns represent the current skills.

Staff members are assigned to activities according to their skills



Skills requirement exampleSkills requirement example



Current skillsCurrent skills

Resource Breakdown Structure

Figure04-12


Resource Breakdown Structure


Used as the basis for identifying the positions and levels that are needed to staff the project.

Used to construct the staffing budget.

Assign as profile


In reality, we cannot presume that the resource is going to work at about the same percent per day for each day of the task. In other words, they are not flat-loaded at a constant rate.

The duration is estimated first and then the work is assigned at different percents

For example, you might assign the worker 75 percent for 20 hours and 50 percent for 20 hours

Order of magnitude estimateOrder of magnitude estimate The number given for the estimate is somewhere

between 25 percent above and 75 percent below the number.

Often used at the very beginning of the estimation process when very little detail is known

Budget estimateBudget estimate Has a range of 10 percent over and 25 percent below

the stated estimate Used during the project planning.

Definitive estimateDefinitive estimate It has a range of 5 percent over and 10 percent below the

stated estimate. Done frequently during project execution when new information

helps further improvement

Estimating Cost


Cost Budgeting: This is the phase when you assign costs to tasks on the

WBS. You take the needed resources and multiply the costs by the

number of hours they are to be used. Is more detailed than cost estimation.

Cost Control Weekly reports of the costs Baseline versus actual

Estimating Cost


The Project Network Diagram

The tasks and the task duration are the basic building blocks needed to construct a graphic picture of the project.

This graphic picture provides you with two additional pieces of schedule information about the project: The earliest time at which work can begin on every task that

makes up the project The earliest expected completion date of the project

the required resources must be available at the times established in this plan.

Envisioning a Complex Project Network Diagram

A project network diagram is a pictorial representation of the sequence in which the project work can be done.

What tasks must be complete before another task can begin?

Now a set of tasks is complete, what task or tasks could come next?

Benefits to Network-Based Scheduling

There are two ways to build a project schedule: Gantt chart Network diagram

Design

Build

Test

Install

time

Gantt Chart

There are two drawbacks to using the Gantt chart: Because of its simplicity, the Gantt chart does not contain

detailed information. You cannot tell from the Gantt chart what must come before and after what.

The Gantt chart does not tell the project manager whether the schedule that results from the Gantt chart completes the project in the shortest possible time or even uses the resources most effectively.

Design

Build

Test

Install

time

Network-based Scheduling – Gantt Charts


Network diagrams

Network diagrams can be used for

Planning.

Implementation: For those project managers who use automated project

management software tools, update the project file with task status and estimate-to-completion data. The network diagram is then automatically updated and can be printed or viewed.

Control

Building the Network Diagram Using thePrecedence Diagramming Method

task-on-the-arrow (TOA) method.

Figure04-13

Task-on-the-arrow (TOA) method

The node at the left edge of the arrow is the event “begin the task,” while the node at the right edge of the arrow is the event “end the task.”

Nodes are numbered sequentially.

One seldom sees this approach used today.

Network-based Scheduling – Task on the Node

Figure04-14


PDM format of a project network diagram

Task on the Node

The basic unit of analysis in a network diagram is the task.

Each task in the network diagram is represented by a rectangle called a task node.

Arrows represent the predecessor/successor relationships between tasks.

ES

EID

LS LF

EF

SLACK

Task Node

Figure04-15


Diagramming Conventions

Figure04-16


Dependency Relationships

A B

A

B

A

B

B

FS: When A finishes, B may start

FF: When A finishes, B may finish

SS: When A starts, B may start

SF: When A starts, B may finishA

Figure04-17


Dependency Relationships

Examples:

FS: When design is complete, programming can begin

FF: When data collection is complete, data entry can be completed

SS: Once the guests start arriving, the food can be brought out

SF: Once the patient real heart starts beating again, the heart lung machine can be turned off

Technical constraints Discretionary constraints Best practice constraints Logical constraints Unique requirements constraints

Management constraints Inter-project constraints Date constraints

No earlier than No later than On this date

Lag variables

Dependency Constraints


Technical constraints

arise because one task (the successor) requires output from another (the predecessor) before work can begin on it.

In the simplest case, the predecessor must be completed before the successor can begin.

Discretionary constraints.

Judgment calls by the project manager that result in the introduction of dependencies.

For example, the data collection and data entry. a team of recent hires will be collecting the data and that the

usual practice is to have them enter the data as they collect it (SS dependency).

This introduces some risk to the process; and because new hires will be doing the data collection and data entry, the project manager decides to use an FS, rather than SS, dependency between data collection and data entry.

Best-practices constraints.

Past experiences that have worked well for the project manager or are known to the project manager based on the experiences of others in similar situations.

For example, consider the dependency between software design and software build tasks.

The safe approach is to complete design before beginning build. But getting to the market faster has become the strategy for survival.

Changing the FS dependency between design and build to an SS dependency

At some point in the design phase, enough is known about the final configuration of the software to begin limited programming work.

Logical constraints.

arise from the project manager’s way of thinking about the logical way to sequence a pair of tasks.

For example, in the design-build scenario There is some concurrency between software design with the

build task.

Part of the software design work, however, involves the use of a recently introduced technology with which the company has no experience.

For that reason, the project manager decides that the part of the design that involves this new technology must be complete before any of the associated build tasks can start.

Unique requirements.

Occur in situations where a critical resource — say, an irreplaceable expert or a one-of-a kind piece of equipment — is involved on several project tasks.

Project manager creates FS dependencies

To ensure that no scheduling conflicts will arise from the use of scarce resources.

Management Constraints

The result of a management-imposed constraint.

For example, suppose the product manager on a software development project is aware that a competitor will soon introduce a new product with similar features to their own. Rather than follow the concurrent design-build strategy, the product

manager expects design changes in response to the competitor’s new product and, rather than risk wasting the programmers’ time, imposes the FS dependency between the design and build tasks.

Management Constraints differ from technical dependencies in that they can be reversed, whereas technical dependencies cannot.

Interproject Constraints

Interproject constraints result when deliverables from one project are needed by another project.

For example, suppose a new piece of test equipment is being manufactured by the same company that is developing the software that will use the test equipment. In this case, the start of the testing tasks in the software development project

depends on the delivery of the manufactured test equipment from the other project.

The dependencies that result are technical but exist between tasks in two or more projects, rather than within a single project.

Interproject constraints arise when a very large project is decomposed into smaller, more manageable projects. (For example, the construction of the Boeing 777)

Date Constraints

Date constraints impose start or finish dates on a task, forcing it to occur according to a particular schedule.

These constraints generally conflict with the schedule that is calculated and driven by the dependency relationships between tasks.

Date constraints come in three types: No earlier than. No later than. On this date.

The result is the creation of a needless complication in the project schedule and later in reporting the status of the project.

Using the Lag Variable

Pauses or delays between tasks are indicated in the network diagram through the use of lag variables.

For example, suppose that you wait 10 days from the date you mail the surveys until you schedule entering the data from the surveys.

You defined an SS dependency with a lag of 10 days.

task B (data entry) can start 10 days after task A (mail the survey) has started.

The Forward Pass – Early Schedule Left to right (start to finish) Determines Early Start and Early Finish ES + duration – 1 = EF

Backward Pass – Late Schedule Right to left (finish to start) Determines Late Start and Late Finish LF - duration + 1 = LS

Paths Through the Network


Paths Through the Network

The combination of these two schedules gives you two additional pieces of information about the project schedule:

1. The window of time within which each task must be started and finished in order for the project to complete on schedule

2. The sequence of tasks that determine the project completion date (the critical path).

Critical path

The critical path can be defined in several ways: The longest duration path in the network diagram

The sequence of tasks whose early schedule and late schedule are the same

The sequence of tasks with zero slack or float

The critical path is the sequence of tasks that must be completed on schedule in order for the project to be completed on schedule.

The tasks that define the critical path are called critical path tasks. Any delay in a critical path task will delay the completion of the

project by the amount of delay in that task.

The Forward Pass

The earliest start (ES) time for a task is the earliest time at which all of its predecessor tasks have been completed and the subject task can begin.

The ES time of tasks with one predecessor task is determined from the earliest finish (EF) time of the predecessor task.

The latest start (LS) and latest finish (LF) times of a task are the latest times at which the task can start or finish without causing a delay in the completion of the project.

Forward Pass Calculations – Early Schedule

Figure04-18


Backward Pass

The window of time between the ES and LF of a task is the window within which the resource for the work must be scheduled or the project completion date will be delayed.

LS is calculated as ((LF – Duration) + One Time Unit).

Backward Pass Calculations – Late Schedule

Figure04-19


Critical Path

Figure04-20


Example

Another example

Another example…

ES LFDuration

SlackTask

Early Start to Late Finish Window

Figure04-21


Slack is the difference between the late finish and the early finish (LF – EF)

Total Slack Time that a task can be delayed without

impacting the early schedule of the project.

Free Slack Time a task can be delayed without

impacting the early schedule of its successor tasks.

Slack Time (also called float)

Do Not Plan to Use Slackto Bail Out the Project!


Critical Path: The longest path or sequence of tasks (in terms

of task duration) through the network diagram The critical path drives the completion date of

the project Critical tasks have zero slack.

Near Critical Path: Tasks not on the critical path with which the team

has little experience, so the duration estimates have large estimation variances.

Project Network Diagram


116


PERT is based on the assumption that an activity’s duration follows a probability distribution instead of being a single value

Three time estimates are required to compute the parameters of an activity’s duration distribution: pessimistic time (tp ) - the time the activity would take if

things did not go well most likely time (tm ) - the consensus best estimate of

the activity’s duration optimistic time (to ) - the time the activity would take if

things did go well

PERT

Mean (expected time): te =tp + 4 tm + to

6

Variance: Vt =2 =tp - to

6

2


PERT

118

Draw the network. Analyze the paths through the network and find the critical

path. The length of the critical path is the mean of the project

duration probability distribution which is assumed to be normal

The standard deviation of the project duration probability distribution is computed by adding the variances of the critical activities (all of the activities that make up the critical path) and taking the square root of that sum

Probability computations can now be made using the normal distribution table.


PERT

119

Determine probability that project is completed within specified time

Z = x -

where = tp = project mean time

= project standard mean time

x = (proposed ) specified time


PERT- probability computation

PERT Example

Consider the following table of activities; immediate predecessor(s) (I.P.); optimistic, most likely, and pessimistic completion times for General Foundry; and the E(ti) and var(ti) for each activity.

ACT I.P. Optimistic Most Likely Pessimistic E(t i) var(ti) A __ 1 week 2 weeks 3 weeks 2 wks. 4/36 B __ 2 3 4 3 4/36 C A 1 2 3 2 4/36 D B 2 4 6 4 16/36 E C 1 4 7 4 36/36 F C 1 2 9 3 64/36 G D,E 3 4 11 5 64/36 H F,G 1 2 3 2 4/36

A2

B3

C2

D4

F3

E4

G5

H 2

ACT I.P. (a) (m) (b) E(ti) var(ti) A __ 1 2 3 2 4/36 B __ 2 3 4 3 4/36 C A 1 2 3 2 4/36 D B 2 4 6 4 16/36 E C 1 4 7 4 36/36 F C 1 2 9 3 64/36 G D,E 3 4 11 5 64/36 H F,G 1 2 3 2 4/36

PERT Example

Inspection of the network discloses three paths thru the project:

A-C-F-H; A-C-E-G-H; and B-D-G-H. Summing the E(ti) on each path yield time thru each path of 9, 15, and 14 weeks, respectively.

With an E(t) = 15 for A-C-E-G-H, this path is defined as the critical path (CP) being the path that govens the completion time of the project .

variance equal to the sum of the variances of its activities only, var(t) = 112/36 = 3.11.

PERT Example

what is the probability of the project requiring in excess of 16 weeks to complete?

P( X > 16) = 1 - P ( X < 16) = 1 - P ( Z < (16 - 15) / 1.76 = .57) = 1 - 0.716

A

B

C

D

E

F

G

H

2

3

2

4

3

4

5

2

0

0

2

3

4

4

8

13 15

13

7

8

4

7

2

3

EF

ES

15

13

8

413

8

2

4

0

1

LF

LS

13

8

10

4

2

4

critical path

Another CPM Example

125

Immed. Optimistic Most Likely PessimisticActivity Predec. Time (Hr.) Time (Hr.) Time (Hr.)

A -- 4 6 8B -- 1 4.5 5C A 3 3 3

D A 4 5 6 E A 0.5 1 1.5 F B,C 3 4 5 G B,C 1 1.5 5 H E,F 5 6 7 I E,F 2 5 8 J D,H 2.5 2.75 4.5 K G,I 3 5 7


PERT Example 2

126

Activity Expected Time Variance A 6 4/9

B 4 4/9 C 3 0 D 5 1/9 E 1 1/36 F 4 1/9 G 2 4/9 H 6 1/9 I 5 1 J 3 1/9 K 5 4/9


PERT Example

127

Activity ES EF LS LF Slack A 0 6 0 6 0

*critical B 0 4 5 9 5 C 6 9 6 9 0 * D 6 11 15 20 9 E 6 7 12 13 6 F 9 13 9 13 0 * G 9 11 16 18 7 H 13 19 14 20 1 I 13 18 13 18 0 * J 19 22 20 23 1 K 18 23 18 23 0 *


PERT Example

darla/smbs/vit 128

Vpath = VA + VC + VF + VI + VK

= 4/9 + 0 + 1/9 + 1 + 4/9 = 2path = 1.414

z = (24 - 23)/(24-23)/1.414 = .71 From the Standard Normal Distribution table:

P(z < .71) = .5 + .2612 = .7612


PERT Example

Replace FS with SS dependencies Focus on critical activities Partitionable activities

Replace a team member with a more skilled person

Add resources From non-critical path tasks to critical path tasks From other projects To where

critical path tasks high-risk tasks tasks with large duration variances

Schedule Compression Techniques


Schedule Compression Iterations

Figure04-22


Schedule compression doesn’t come free.

Schedule Compression

What is the impact on the project due to schedule compression?


DO NOT PAD ACTIVITY DURATION A percentage of total project work hours (5% to

10%) The last activity in the project A schedule contingency for the unexpected

delays Make it visible and manage it

Management Reserve


effective project management: traditional, agile, extreme

Documents

project ch04

project description

project planhow

project planning session

detailed plan

effective project management

whiteboard ch04

sticky notes ch04