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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 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
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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 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 Diagram relating components radiating out from central element (Ref: Wikipedia article)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 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
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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 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
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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 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
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“Early estimates will not be as good as later estimates.”
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Types of resources People Facilities Equipment Money Materials
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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
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Used to estimate resource and costs by showing the positions needed for a particular project
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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)
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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
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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
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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
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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
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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 Tasks Task Duration 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
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Early Method – Task-On-the-Arrow (TOA)
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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 Start Task has no predecessor End Task has no successor Diagram the connections
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Diagramming connections between tasks
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Four Kinds of Task Dependencies
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Technical Constraints Discretionary 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 Early schedule – use Forward Pass Late schedule – use Backward Pass Forward PassBackward 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 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
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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 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
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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)
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