Prof. Roy Levow
Session 4

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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

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

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

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

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Small Projects – Consider mindmapping
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Diagram relating components radiating out from central element (Ref: Wikipedia article )
Large Projects – Intermediate WBS
Adaptive and Extreme Projects – Iterative WBS

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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

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

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Noun-type: In terms of the components of the deliverable
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Physical Decomposition
Functional Decomposition
Verb-type: In terms of the actions that must be done to produce the deliverable
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Design-build-test-implement
Objectives
Organizational: In terms of the units that will create the deliverable
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Geographic
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Departmental
Business Process

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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

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The difference between Duration and Work
Effort

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Crashing the task – adding more resources to preserve duration
Diminishing returns
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Crashpoint: adding more resources INCREASES task duration
Considerations
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Not always feasible (Can nine women have a baby in one month?)
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Communication overhead increases
Risk increases

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

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Similarity to other activities
Historical Data
Expert Advice
Delphi Technique
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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
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Combination of Delphi and Three-Point techniques

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

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Types of resources
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People
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Facilities
Equipment
Money
Materials

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Skills Matrices
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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

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Three variables influence Duration Estimate
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Duration
Total amount of work (hours/days)
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Percent per day that person can devote to task
Methods for Estimating Duration
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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
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Assign as a Duration and Percent/Day
 10 days X 0.50 = 5 person days
Assign as a Profile (when using multiple resources)

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Resource Planning
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Trading money for time (depends on skill level)
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Part-time workers (think of ramp-up time)
Don’t overschedule resources
Cost Estimating
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Order of magnitude estimate
 Estimate is 25% above and 75% below final number
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Budget estimate
 Estimate is 10% above and 25% below final number
Definitive estimate
 Estimate is 5% above and 10% below final number

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Cost Budgeting – Assign costs to tasks on the
WBS
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Cost Control – Two major issues
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How often report of costs is needed
 Depends on risk and need to spot developing problems
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Use of a cost baseline to spot cost variances when you receive actual figures

Advice from the author:
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Get it roughly right
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Spend more effort on front-end activities than on back-end activities
Consensus is all that is needed

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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

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Definition: “A pictorial representation of the sequence in which the project work can be done.”
What is needed to construct diagram
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Tasks
Task Duration
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Earliest time to start task
Earliest expected completion date for the project

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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

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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)

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First, every task in the WBS has a task node

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Second, determine the sequence of tasks
Every task has at least one predecessor and at least one successor
EXCEPT
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Start Task has no predecessor
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End Task has no successor
Diagram the connections

Diagramming connections between tasks

Four Kinds of Task Dependencies

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Technical Constraints
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Discretionary
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Best-Practices
Logical
Unique
Management Constraints
Interproject Constraints
Date Constraints

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

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Compute two schedules
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Early schedule – use Forward Pass
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Late schedule – use Backward Pass
Forward Pass Backward Pass
What’s different?

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“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

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

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Second method – Compute the slack time
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The amount of delay (in time units) in starting a task that will not affect the project completion date
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Difference between late finish and early finish of a slack time
Do not include holidays, weekends, and similar such time
Two types of slack
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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

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Crashing the schedule: necessary when the initial project network diagram shows a projected completion date that is later than the requested completion date.
Strategies
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Examine the Critical Path to see if you can move tasks off the Critical Path
Partition tasks into parallel subtasks
Concerns
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Increase in risk
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More communication and coordination needed

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Padding task duration
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Individual task level
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Project level
Bad at the task level
BUT, good at the project level
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Accounts for risk
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Incentive (management reserve time not used can be the basis for bonus)