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COMP442 Project Management. Session Objectives. Planning & scheduling Work Breakdown Structure Realistic Estimating Critical Path. Project Time Management Processes. Project time management involves processes required to ensure timely completion of a project Processes include:
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Session Objectives • Planning & scheduling • Work Breakdown Structure • Realistic Estimating • Critical Path
Project Time Management Processes • Project time management involves processes required to ensure timely completion of a project • Processes include: • Activity definition • Activity sequencing • Activity duration estimating • Schedule development • Schedule control
Estimating: Work Breakdown Structure • “Project best understood by breaking it down into its parts” • Work Breakdown Structure (WBS) • powerful tool for doing this (not just a task list) • defines the total scope of the project • fundamental to much of project planning & tracking • Start at top, progressively break work down (tree structure) into work packages • Roll up the packages for bottom up estimating • Packages give clear work assignments
Intranet WBS in Tabular Form 1.0 Concept 1.1 Evaluate current systems 1.2 Define Requirements 1.2.1 Define user requirements 1.2.2 Define content requirements 1.2.3 Define system requirements 1.2.4 Define server owner requirements 1.3 Define specific functionality 1.4 Define risks and risk management approach 1.5 Develop project plan 1.6 Brief web development team 2.0 Web Site Design 3.0 Web Site Development 4.0 Roll Out 5.0 Support
Intranet WBS and Gantt Chart Project 98 file
Realistic Estimating (Frame) • Lots of reasons for poor estimates • inexperience, technical problems, changes optimists, low-balling, politics • Bottom-up cost estimating • rollup the WBS packages • Top-down or Parametric estimating • from experience to complex models
Realistic Estimating (cont.) • Which technique is better? • ideally use both • early on don’t have WBS so must use top-down • accuracy of top-down depends on availability/quality of historical data • building complete WBS can be expensive, but guesses can be even more costly
Deliverables and Milestones • Deliverables • Tangible, verifiable work products • Reports, presentations, prototypes, etc. • Milestones • Significant events or achievements • Acceptance of deliverables or phase completion • Cruxes (proof of concepts) • Quality control • Keeps team focused
Developing the WBS • Develop work packages for each of the phases and deliverables defined in the Deliverable Structure Chart (DSC)
Software Engineering Metrics • Lines of Code (LOC) • Function Points
Lines of Code (LOC) • Most traditionally used metric for project sizing • Most controversial • Count comments? • Declaring variables? • Efficient code vs. code bloat • Language differences • Easier to count afterwards than to estimate
The Mythical Man-Month – Frederick Brooks • 0ur techniques of estimation are poorly developed.More seriously, they reflect an unvoiced assumption which is quite untrue i.e., that all will go well. • Our estimating techniques fallaciously confuse effort with progress, hiding the assumption that men and months are interchangeable.
The Mythical Man-Month – Frederick Brooks 3. Because we are uncertain of our estimates,software managers often lack the courteous stubbornness of Antoines chef 4. Schedule progress is poorly monitored.Techniques proven and routine in other engineering disciplines are considered radical innovations in software engineering
The Mythical Man-Month – Frederick Brooks 5. When schedule slippage is recognized, the natural tendency (and traditional) response it to add more manpower. Like dousing a fire with gasoline,this makes matters worse, much worse. More fire requires more gasoline, and thus begins a regenerative cycle which ends in disaster.
Brooks Law: “Adding manpower to a late software project makes it later.”
Scheduling Tools & Methods • Gantt Charts • Critical Path Method (CPM) • Program Evaluation and Review Technique (PERT)
Developing a Project Schedule • Base documents • Project charter – start/end dates (tentative), budget • Scope statement – what will be done (& not done) • Activity definitions • develop detailed WBS • plus supporting explanations to understand all work to be done
Activity Sequencing • Review activities & determine dependencies • Mandatory dependencies: inherent in the nature of the work; hard logic • Discretionary: defined by the project team; soft logic • External: involve relationships between project and external activities • Must determine dependencies to use critical path analysis
Gantt Charts • Created 1800 • Standard format for displaying project schedules • activities, durations, start/end finish dates displayed in calendar format • Advantages • enforces planning • easy to create & understand • preferred for summary/exec-level information
Gantt Charts (cont.) • Symbols include: • black diamond: milestones • Thick black bars: summary tasks • Lighter horizontal bars: tasks • Arrows: dependencies between tasks • Bar Charts • Simplified version • Serve similar function
Sample Tracking Gantt Chart white diamond: slipped milestone two bars: planned and actual times
Critical Path Method (CPM) • Developed 1957 • CPM diagram shows activities, durations, start/end dates & sequence in which they must be completed • Critical path for project is the series of activities that determines the earliest time by which project can be completed • Critical path is longest path through network diagram, has least (zero) slack or float
CPM (cont.) • Critical path helps you make schedule trade-offs • Slack or float amount of time activity can be delayed without delaying early start of dependent activities
Simple Example of Determining Critical Path • consider following network diagram • assume all times in days a. How many paths are on this network diagram? b. How long is each path? c. Which is the critical path? d. What is the shortest amount of time needed to complete this project? Activity-on-Arrow (AOA) Network Diagram
Precedence Diagramming Method (PDM) • Activities are represented by boxes • Arrows show relationships between activities • More popular than ADM method as used by PM software • Better at showing different types of dependencies
Critical Path • Longest path • Shortest time project can be completed • Zero slack (or float) • The amount of time an activity can be delayed before it delays the project • Must be monitored and managed! • PM can expedite or crash • Can fast track • The CP can change • Can have multiple CPs
Techniques for Shortening a Project Schedule • Shortening durations of critical tasks: • add more resources • change their scope • Crashing tasks by obtaining the greatest amount of schedule compression for the least incremental cost • Fast tracking tasks by doing them in parallel or overlapping them
PERT • Developed 1959 for Polaris project • Similar to CPM but addresses uncertainties in task durations • Uses probabilistic time estimates – optimistic, most likely, pessimistic estimates of activity durations
PERT Formula and Example • PERT weighted averageformula: optimistic time + 4X most likely time + pessimistic time 6 • Example: PERT weighted average = 8 workdays + 4 X 10 workdays + 24 workdays = 12 days 6 where 8 = optimistic time, 10 = most likely time, and 24 = pessimistic time
Activity Analysis for PERT 30 days 31.6 days
Selecting Scheduling Approach • Consider project size, risk and complexity • Gantt • senior management • smaller, less complex projects • CPM • medium size/complexity/risk • PERT • high risk projects • medium to high complexity