Scheduling

SchedulingProject manager's objectivesSchedulingPrimary objectives

Secondary objectivesSchedulingSome Thumb RulesSchedulingPrecedenceA task that must occur before another is said to have precedence of the otherConcurrence:Concurrent tasks are those that can occur at the same time (in parallel)Leads & Lag TimeDelays between activitiesTime required before or after a given taskMilestonesHave a duration of zeroIdentify critical points in your scheduleShown as inverted triangle or a diamondOften used at review or delivery timesOr at end or beginning of phasesEx: Software Requirements Review (SRR)Ex: User Sign-offCan be tied to contract termsSchedulingDeliverable: A deliverable is a measurable and verifiable work products.

In current practice sometimes milestone and deliverables are used interchangeably (both used to identify products - milestones may represent key-products)

Slack & FloatFloat & Slack: synonymous termsFree SlackSlack an activity has before it delays next taskTotal SlackSlack an activity has before delaying whole projectSlack Time TS = TL TETE = earliest time an event can take placeTL = latest time it can occur w/o extending projects completion dateScheduling TechniquesMathematical AnalysisScheduling TechniquesNetwork DiagramsDeveloped in the 1950sA graphical representation of the tasks necessary to complete a projectVisualizes the flow of tasks & relationshipsPERTProgram Evaluation and Review TechniqueCPMCritical Path MethodSometimes treated synonymouslyAll are models using network diagramsScheduling TechniquesTwo classic formatsAOA: Activity on ArrowAON: Activity on NodeEach task labeled withIdentifier (usually a letter/code)Duration (in std. unit like days)There are other variations of labelingThere is 1 start & 1 end eventTime goes from left to rightNetwork DiagramsScheduling Techniques

Scheduling TechniquesAOA consists ofCircles representing EventsSuch as start or end of a given taskLines representing TasksThing being done Build UIa.k.a. Arrow Diagramming Method (ADM)AONTasks on NodesNodes can be circles or rectangles (usually latter)Task information written on nodeArrows are dependencies between tasksa.k.a. Precedence Diagramming Method (PDM)Scheduling TechniquesCritical PathThe specific set of sequential tasks upon which the project completion date dependsor the longest full pathAll projects have a Critical PathAccelerating non-critical tasks do not directly shorten the scheduleCritical Path MethodThe process for determining and optimizing the critical pathNon-CP tasks can start earlier or later w/o impacting completion dateNote: Critical Path may change to another as you shorten the current one.Scheduling TechniquesForward PassTo determine early start (ES) and early finish (EF) times for each taskWork from left to rightAdding times in each pathRule: when several tasks converge, the ES for the next task is the largest of preceding EF timesBackward PassTo determine the last finish (LF) and last start (LS) timesStart at the end nodeCompute the bottom pair of numbersSubtract duration from connecting nodes earliest start timeScheduling TechniquesNetwork DiagramsAdvantagesShow precedence wellReveal inter-dependencies not shown in other techniquesAbility to calculate critical pathAbility to perform what if exercisesDisadvantagesDefault model assumes resources are unlimitedYou need to incorporate this yourself (Resource Dependencies) when determining the real Critical PathDifficult to follow on large projectsScheduling TechniquesNetwork DiagramsDependenciesMandatory Dependencies

Hard logic dependenciesNature of the work dictates an orderingEx: Coding has to precede testingEx: UI design precedes UI implementationDiscretionary Dependencies

Soft logic dependenciesDetermined by the project management teamProcess-drivenEx: Discretionary order of creating certain modulesScheduling TechniquesNetwork DiagramsDependencies

External Dependencies

Outside of the project itselfEx: Release of 3rd party product; contract sign offEx: stakeholders, suppliers, Y2K, year endResource Dependencies

Two task rely on the same resourceEx: You have only one DBA but multiple DB tasksScheduling TechniquesFinish-to-Start (FS)B cannot start till A finishesA: Construct fence; B: Paint FenceStart-to-Start (SS)B cannot start till A startsA: Pour foundation; B: Level concreteFinish-to-Finish (FF)B cannot finish till A finishesA: Add wiring; B: Inspect electricalStart-to-Finish (SF)B cannot finish till A starts (rare)Task Dependency Relationship

Scheduling TechniquesProgram Evaluation and Review Technique

Based on the idea that estimates are uncertainTherefore uses duration rangesAnd the probability of falling to a given range

Uses an expected value (or weighted average) to determine durations

Use the following methods to calculate the expected durations, then use as input to your network diagramPERTScheduling TechniquesPERTStart with 3 estimates

OptimisticWould likely occur 1 time in 20Most likelyModal value of the distributionPessimisticWould be exceeded only one time in 20Scheduling TechniquesPERTCombined to estimate a task duration

Scheduling TechniquesPERTAdvantagesAccounts for uncertaintyDisadvantagesTime and labor intensiveAssumption of unlimited resources is big issueLack of functional ownership of estimatesMostly used on large, complex projectScheduling TechniquesCPM vs. PERTBoth use Network DiagramsCPM: deterministicPERT: probabilisticCPM: one estimate, PERT: three estimatesPERT is infrequently usedScheduling TechniquesProject DurationHow can you shorten the schedule?ViaReducing scope (or quality)Adding resourcesConcurrency (perform tasks in parallel)Substitution of activitiesScheduling TechniquesCompression TechniqueShorten the overall duration of the projectCrashingLooks at cost and schedule tradeoffsGain greatest compression with least costAdd resources to critical path tasksChanging the sequence of tasksFast TrackingOverlapping of phases, activities or tasks that would otherwise be sequentialInvolves some riskMay cause reworkScheduling TechniquesExampleUsing the table below, draw the network diagram and answer the questions.ActivityEstimate in WeeksStart A3Start B9A C3B CDummyB E2C D2C E1E End4D End2Scheduling TechniquesExampleStartACDEndBE3322924The critical path is Start B, B E, and E End.1Scheduling TechniquesClass ExerciseJ2Install Inc TwoKE5Install Inc OneFE, I6Test Inc TwoJA, B7Analyze Inc TwoGF, KHGDCBANonePred.2Close out projectL4Code Inc TwoI5Design Inc TwoH10Test Inc OneE7Code Inc OneD8Design Inc OneC3Analyze Inc OneB4/13Establish incrementsAFinishStartDurationTask NameTask #Scheduling TechniquesSolutionJ5/95/82Install Inc TwoKE5/65/25Install Inc OneFE, I5/75/26Test Inc TwoJA, B4/134/77Analyze Inc TwoGF, KHGDCBANonePred.5/115/102Close out projectL4/224/194Code Inc TwoI4/184/145Design Inc TwoH5/14/2210Test Inc OneE4/214/157Code Inc OneD4/144/78Design Inc OneC4/64/43Analyze Inc OneB4/34/13Establish incrementsAFinishStartDurationTask NameTask #A. EstablishIncrements3B. AnalyzeInc One3C. DesignInc One8D. CodeInc One7F. InstallInc One5G. AnalyzeInc Two7H. DesignInc Two5I. CodeInc Two4K. InstallInc Two2L. Close outProject2E. TestInc One10J. TestInc Two6Scheduling TechniquesSolutionA. EstablishIncrements3B. AnalyzeInc One3C. DesignInc One8D. CodeInc One7F. InstallInc One5G. AnalyzeInc Two7H. DesignInc Two5I. CodeInc Two4K. InstallInc Two2L. Close outProject2E. TestInc One10J. TestInc Two6Task network and the critical path:A-B-C-D-E-J-K-LCost ControlEarned Value AnalysisEarned Value Analysis Terms to KnowAcronymTermInterpretationPVPlanned ValueWhat is the estimated value of the work planned to be done?EVEarned ValueWhat is the estimated value of the work actually accomplished?ACActual CostWhat is the actual cost incurred for the work accomplished?BACBudget at CompletionHow much did we BUDGET for the TOTAL project effort?EACEstimate at CompletionWhat do we currently expect the TOTAL project to cost?ETCEstimate to CompleteFrom this point on, how much MORE do we expect it to cost to finish the project?VACVariance at CompletionHow much over or under budget do we expect to be at the end of the project?Earned Value Analysis FormulaeNameFormulaInterpretationCost Variance (CV)EV AC-ve is over budget, +ve is under budget.Schedule Variance (SV)EV PV-VE is behind schedule, +VE is ahead of schedule.Cost Performance Index (CPI)EV/ACWe are getting Rs.. Worth of work out of every Re 1 spent. Funds are or are not being used efficiently.Schedule Performance Index (SPI)EV/PVWe are (only) progressing at .. % of the rate originally planned.Estimate at Completion (EAC)BAC/CPI

AC+ETC

AC + (BAC EV)As of now, how much do we expect the total project to cost? Rs..

Used if no variance from the BAC have occurred or you will continue at the same rate of spending.Actual plus a new estimate for remaining work. Used when original estimate is fundamentally flawed.Actual to date plus remaining budget. Used when current variances are thought to be atypical of the future.Earned Value Analysis FormulaeNameFormulaInterpretationEstimate at Completion (EAC)AC +[ (BAC EV)/CPI]As of now, how much do we expect the total project to cost? Rs..

Actual to date plus remaining budget modified by performance. Used when current variances are thought to be typical of the nature.Estimate to Complete (ETC)EAC ACHow much more will the project cost?Variance at Completion (VAC)BAC EACHow much over or under budget will we be at the end of the project?Earned Value Analysis ExampleYou have a project to build a new fence. The fence is four sided as shown. Each side is to take one day to build and is budgeted for Rs 1000 per side. The sides are planned to be completed one after another. Today is the end of day three.

Using the project chart below, calculate EV, etc.ActivityDay 1Day 2Day 3Day 4Status, End of Day 3Side 1S--------FComplete, spent Rs 1000Side 2S----------PF-----FComplete, spent Rs 1200Side 3PS----S-----PF50% done,Spent Rs 600Side 4PS--------PFNot yet startedKey S = Actual Start, F = Actual Finish, PS = Planned Start, PF = Planned FinishEarned Value Analysis ExampleWhat is:CalculationAnswerInterpretationPV1000 + 1000 + 10003000We should have done Rs 3000 worth of workEVComplete, Complete, Half done = (1000+1000+500)2500We have actually completed Rs 2500 worth of workAC1000 + 1200 + 6002800We have actually spent Rs 2800.BAC1000 + 1000 + 1000 + 10004000Our project budget is 4000.CV2500 2800300We are over budget by Rs 300.CPI2500 divided by 2800.893We are getting only 89 paise out of every Re we put into the project.SV2500 3000500We are behind schedule.SPI2500 divided by 3000.833We are only progressing at 83% of the rate planned.EAC4000 divided by .8934479We currently estimate that the total project will cost Rs 4479.ETC4479 28001679We need to spend Rs 1679 to finish the project.VAC4000 4479479We currently expect to be Rs 479 over budget when the project is completed.