2 The Plan versus a Schedule Defines the activitiesDocuments the interaction between activitiesEstimates the duration for completing each activityAnalyzes the sequences, duration and resource requirements to crate a project scheduleThe scheduleDetermine start and finish dates for project activitiesOften must be iterated(along with processes that are the input) especially the duration estimating
3 Project Planning Techniques Provide regular status updates to stakeholdersInclude team members in planning sessions and plan preparationProvide various alternatives to managementScope constrained alternativesTime constrained alternativesResources alternativesPlan to planObtain plan approval before beginning execution
4 Work Products for Planning Task ListWork BreakdownStructureProject ObjectivesPrecedenceGraphCPM DiagramGantt Chart
5 Getting the Planning Process Started Optional: for a product-oriented project, it may be useful to begin with a product listProduct ListTask ListWork BreakdownStructureProject ObjectivesPlanning depends on estimates of the work required and the way it will be organized.The planning process is driven by the project objectives
6 From Task List to WBS Task List WBS Task A Task B Task C Task D Task E Task FWBSOverall TaskSubTask 1SubTask 2Task BTask CTask ASubTask 2.1Task FTask ETask Dadd management
7 WBS as an Estimation Tool Bottom-Up Estimating Effort for smaller tasks can be more accurately estimated than larger onesEstimate all the “primitive” tasks first (those at the bottom of the WBS – with no subtasks of their own). PMBOK * calls these work packages.Combine these estimates to get an overall estimate or estimates for major subtasksTrack actuals against estimates at the task level to improve your estimating skillsUse this data to create a useful experiential estimation databaseProject Management Book of Knowledge
8 Precedence GraphThe precedence graph captures predecessor or sequencing information for all tasks in the WBSUsed as an intermediate step toward a CPM diagramThe process used to create the precedence graph is referred to as PDM (Precedence Diagram Method) in the PMBOK.Work BreakdownStructurePrecedenceGraph
9 Precedence GraphActivity PActivity MActivity OActivity QActivity SActivity NActivity RActivity N must complete before Activity R can begin, and so on.
10 Effort and DurationCPM (Critical Path Method) Diagrams are derived from Precedence GraphsTo accomplish this, we must translate effort estimates into duration estimatesEffort defines the total required number of time units (often measured in hours) to complete a taskDuration refers to the calendar time (often in days or weeks) required to complete task
11 Effort and Duration (cont’d) Effort is distributed over a durationThis is done by assigning some particular number of persons to the task at various timesOr, we can assign percentages of one or more persons’ time to the task at various times
12 Effort, Duration, and Resource Allocation For example, a 750 hour effort would have a 10-week duration if 2 persons were allocated to it fulltime (assuming a fulltime week = 37.5 hours) for that periodHowever, this same effort could result in drastically different durations, with different resource allocations:40 weeks – if 50% of a person’s time is allocated to it20 weeks -- if 1 person is allocated to it fulltime15 weeks -- with1 person fulltime for 10 weeks, then 2 persons fulltime for the next 5 weeks5 weeks – with 4 persons allocated to it fulltime
13 Effort, Duration, and Resource Allocation (cont’d) It is important to remember that the required effort is just one factor that goes into making a duration estimate.We’ve all heard it:If one woman can produce a baby in 9 months, how soon can 9 women produce a baby?
14 Effort, Duration, and Float (Slack) If we allocate resources so that a task is completed before it is absolutely necessary for all the other task(s) waiting for it to complete, we say that we have built float or slack time into our scheduleFloat adds flexibility to a project’s schedule and hence it is important to recognize when it is possibleThe Critical Path Method (CPM) Diagram captures this feature of a project
15 CPM DiagramsAccording to the PMBOK:PMBOK View“The Critical Path Method (CPM) is a network analysis technique used to predict project duration by analyzing which sequence of activities (which path) has the least amount of scheduling flexibility (the least amount of float). Early dates are calculated by means of a forward pass, using the specified start date. Late dates are calculated using a backward pass, starting from a specified completion date – usually the forward pass calculated project early finish date.”
16 Adding More Information to the Precedence Graph – CPM Diagrams EarliestStartEarliestFinishTaskDurationFloatLatestStartLatestFinishPrecedenceGraphAdd this information for each nodein the Precedence GraphCPM Diagram
17 Terms for CPM Diagrams For each node: D = Estimated Duration ES = Early Start DateES = Earliest finish time for all preceding eventsEF =Early Finish DateEF = ES + DLF =Late Finish DateLF = Latest start time of all succeeding eventsLS =Late Start DateLS = LF - DF = FloatF = LF - EF OR F = LS - ESF = The time an activity’s start or finish can be delayed without delaying project completion
18 Computing Terms for CPM Diagram Nodes D is an estimate (must be known)Determine ES = Early StartES = Earliest finish time for all preceding eventsDetermine LF =Late FinishLF = Latest start time of all succeeding eventsThen we compute LS, EF, and F
19 CPM Diagram Nodes -- Example early start(determined byearliest finishfor all precedingactivities)early finish (= 4 + 3)24 weeks7 weeksTask3 weeks2 weeks1durationfloat (= 9 – 7 or = 6 – 4)6 weeks9 weeks3late finish (determinedby the latest start forall succeeding activities)late start(= 9 – 3)Add this type of information for each node
20 Method for Computing CPM Diagrams All activities must be assigned durations before you beginStart with the activities that have no preceding activities and assign their early start times to be 0 (there may be only one of these)Work from left to right and compute the early start and early finish times for all nodes – this is called the forward passThe largest early finish time will determine the minimum time for the project to completeAll activities with no succeeding activities will get this value as their latest finish times (there may be only one of these). Assign each of these activities to have 0 floatUse this information to work from right to left assigning late finish times and late start times for all nodes – this is called the backward passNow you can quickly compute float for all nodes
21 Team Activity 1: CPM Diagram Consider the CPM Diagram (partial) given on the next slideComplete the diagram by determining the missing information for each node.
23 Critical PathsIf an activity that has 0 float slips, the entire project will slip by that amountThis is why activities that have 0 float are said to be on a critical pathThere may be multiple critical paths for a projectMany practitioners establish some threshold amount of float (suitably small) and compute near-critical paths as well
24 Critical Paths (cont’d) Note that critical (and near-critical) paths are dynamic and change as the actual (as opposed to estimated) schedule unfoldsCritical (and near-critical) paths must be recomputed each time there is an activity slippage anywhere in the schedule that is larger than that activity’s float
25 Why Compute Critical Paths? Can be used to focus resources and attention more efficiently and effectivelyBest resources can be assigned to critical path activitiesAllows project manager to monitor crucial activities more closelyHelps prioritize risks, so risk mitigation activities can be focused on the most important potential risk events“Near-critical” tasks can also be identified and tracked
26 Why Compute Critical Paths? (cont’d) Schedule “emergencies” can be addressed by “crashing” or fast-tracking critical path activitiesCrashing means compressing activity durationFast-tracking means doing things in parallelDanger in crashing or fast-tracking is increased risk
27 Team Activity 2: Critical Paths Consider the CPM Diagram you completed in the previous activity.What is the shortest possible duration for the project?Identify the critical path (or paths).Consider questions 3 and 4 independently of each other.If Procurement slips 3 weeks, what is the impact on the project duration? What happens to the critical pathIf Beta Test slips 2 weeks (with no other slippage), what is the impact on the project duration?
28 Team Activity #3A project has been defined to contain the following list of activities along with their required times for completionDraw a CPM diagram for the activitiesCalculate the earliest completion timeShow the critical pathWhat would happen if activity 6 were revised to take 6 weeks instead of 1 weekActivityImmediate activityWeeksPredecessors1Collect requirements2-Analyze processes3Analyze data4Design processes75Design data6Design screens3, 4Design reports4, 58Program6. 79Test and document10Install8 , 9
29 Team Activity #4Look at the activities outlined in Team Activity 3 (see below). Assume that your team is in its first week of the project and has discovered that each of the activity duration estimates is wrong. Activity 2 will take only 2 weeks to complete . Activity 4 and 7 will each take three times longer than anticipated. All other activities will take twice as long to complete. In addition a new activity, number 11- Feedback, has been added. It will take 1 week to complete and its immediate predecessors are activities 10 and 9.Adjust the CPM diagram andRecalculate the earliest expected completion time
30 Gantt Charts Created from CPM diagrams Capture scheduling information in a bar chart formatDynamic Gantt charts (that is, those that are updated frequently) are an excellent tool to ascertain the status of a project at a given timeGood tool for estimating resource needs in a given time frameCPM DiagramGantt Chart
31 Gantt Charts – An Example date (week #)tasksT1T2T3T4T5criticalpathfloat
32 Team Activity #5: Gantt Chart Construct a Gantt chart for your CPM diagram created in Activity 3Create a Gantt chart from your CPM Diagram.What kind of resources do you anticipate needing in week 6?Can you tell how many resources you will need of each type/category? Hint: Are duration and effort the same?
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