Prof. Roy Levow

Session 4

The Work Breakdown Structure Uses for the WBS Generating the WBS Six Criteria to Test for Completeness in

the WBS Approaches to Building the WBS Representing the WBS

“A hierarchical description of the work that must be done to complete the project as defined in the Project Overview Statement.”

Inputs POS Requirements Document

Terms Activity: Chunk of work Tasks: Smaller chunk of work. Activities are

made up of tasks Work Package: Complete description of how the

tasks that make up the activity will actually be done

The process of breaking down work into a hierarchy of activities, tasks, and work packages

Uses

• Estimate Duration

• Determine Resources

• Schedule Work

Thought Process Tool Architectural Design Tool Planning Tool Project Status Reporting Tool

Top-Down Approach: Start with goal and continue to partition work until it has been sufficiently defined Team Approach Variation Subteam Approach Variation

Bottom-Up Approach: First-level tasks are identified. Then groups are formed around first-level tasks where these groups brainstorm the activities needed to complete the first-level task.

Small Projects – Consider mindmapping Diagram relating components radiating out

from central element (Ref: Wikipedia article) Large Projects – Intermediate WBS Adaptive and Extreme Projects – Iterative

WBS

Status/Completion is measurable The activity is bounded The activity has a deliverable Time and cost are easily estimated Activity duration is within acceptable

limits Work assignments are independent

Seventh Criteria – Project manager’s judgment that the WBS is not complete

Stopping Before Completion Criteria Are Met

Decomposing Beyond Completion of the Criteria

Noun-type: In terms of the components of the deliverable Physical Decomposition Functional Decomposition

Verb-type: In terms of the actions that must be done to produce the deliverable Design-build-test-implement Objectives

Organizational: In terms of the units that will create the deliverable Geographic Departmental Business Process

Outline Estimating Duration Estimating Resource Requirements Estimating Duration as a Function of

Resource Availability Estimating Cost Using a JPP Session to Estimate Duration,

Resource Requirements, and Cost

The difference between Duration and Work Effort

Crashing the task – adding more resources to preserve duration

Diminishing returns Crashpoint: adding more resources

INCREASES task duration Considerations

Not always feasible (Can nine women have a baby in one month?)

Communication overhead increases Risk increases

Varying skill levels Unexpected events Efficiency of work time Mistakes and misunderstandings Common cause variation

Similarity to other activities Historical Data Expert Advice Delphi Technique

Group of experts individually estimate duration

Then, average of the estimates is calculated

Do it two more times Three-Point Technique

most optimistic estimate, most pessimistic estimate, and most likely estimate, which are then averaged

Wide-band Delphi Technique Combination of Delphi and Three-Point

techniques

“Early estimates will not be as good as later estimates.”

Types of resources People Facilities Equipment Money Materials

Skills Matrices Skills needed inventory Skills currently on hand inventory

Skill Categories: uniform listing of skills Skill Levels: level of expertise in a particular skill

Used to estimate resource and costs by showing the positions needed for a particular project

Three variables influence Duration Estimate Duration Total amount of work (hours/days) Percent per day that person can devote to task

Methods for Estimating Duration Assign as a Total Work and a Constant

Percent/Day 40 hours / 0.50 = 80 hours

Assign as a Duration and Total Work Effort 5 person days / 10 days = 0.5

Assign as a Duration and Percent/Day 10 days X 0.50 = 5 person days

Assign as a Profile (when using multiple resources)

Resource Planning Trading money for time (depends on skill

level) Part-time workers (think of ramp-up time) Don’t overschedule resources

Cost Estimating Order of magnitude estimate

Estimate is 25% above and 75% below final number Budget estimate

Estimate is 10% above and 25% below final number Definitive estimate

Estimate is 5% above and 10% below final number

Cost Budgeting – Assign costs to tasks on the WBS

Cost Control – Two major issues How often report of costs is needed

Depends on risk and need to spot developing problems

Use of a cost baseline to spot cost variances when you receive actual figures

Advice from the author: Get it roughly right Spend more effort on front-end activities

than on back-end activities Consensus is all that is needed

Outline The Project Network Diagram Building the Network Diagram Using the

Precedence Diagramming Method Analyzing the Initial Project Network

Diagram Using the JPP Session to Construct and

Analyze the Network

Definition: “A pictorial representation of the sequence in which the project work can be done.”

What is needed to construct diagram Tasks Task Duration Earliest time to start task Earliest expected completion date for the

project

Older than the project network diagram Rectangular bars that show the duration

by length Placed along a timeline in sequence Does not indicate what task needs to be

done before and after a task Does not indicate if the project planning

is most effective or efficient

Planning – Visual overview of the project that is easy to use for scheduling

Implementation – Software exists that automatically updates task dates and duration

Control – Project manager can better schedule tasks and spot variances

Early Method – Task-On-the-Arrow (TOA)

Precedence Diagramming Method (PDM)

First, every task in the WBS has a task node

Second, determine the sequence of tasks Every task has at least one predecessor

and at least one successor EXCEPT

Start Task has no predecessor End Task has no successor

Diagram the connections

Diagramming connections between tasks

Four Kinds of Task Dependencies

Technical Constraints Discretionary Best-Practices Logical Unique

Management Constraints Interproject Constraints Date Constraints

Pauses or delays between tasks Can be intentional Also created by constraints

Compute two schedules Early schedule – use Forward Pass Late schedule – use Backward Pass

Forward Pass Backward Pass

What’s different?

“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 Determines the Completion Date of the Project

First method – add up all of the path’s durations. The longest one is the critical path.

Second method – Compute the slack time The amount of delay (in time units) in starting

a task that will not affect the project completion date

Difference between late finish and early finish of a slack time

Do not include holidays, weekends, and similar such time

Two types of slack Free slack – amount of delay for a task without

causing a delay in the early start of immediate successor task(s)

Total slack – amount of delay for a task without delaying the project completion date

Crashing the schedule: necessary when the initial project network diagram shows a projected completion date that is later than the requested completion date.

Strategies Examine the Critical Path to see if you can

move tasks off the Critical Path Partition tasks into parallel subtasks

Concerns Increase in risk More communication and coordination needed

Padding task duration Individual task level Project level

Bad at the task level BUT, good at the project level

Accounts for risk Incentive (management reserve time not used

can be the basis for bonus)