PM项目管理9预估进度3PPT文件格式下载.ppt

PM项目管理9预估进度3PPT文件格式下载.ppt

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ProjectManagement,ProjectSchedulingIII,2011春夏学期授课版,2,Agenda,PERTanalysis计划评审技术分析PDM前导图法ResourceLevel资源水平,ProgramEvaluationandReviewTechnique（PERT）,项目时间管理的另一项技术,2011春夏学期授课版,4,PERTversusCPM,CPMisdeterministic确定时间估算OnedurationforeachprojectactivityProjectdurationthereforedeterministiconevalue与项目持续时间等长的定值估算PERTisprobabilistic概率时间估算Threedurationforeachprojectactivitytoestablish“expected”durationProjectdurationthereforeprobabilisticarangeofpossiblevaluesforprojectduration具体活动历时估算存在很大不确定性时，用来估算项目历时的技术,2011春夏学期授课版,5,PERTversusCPM,Bothdevelopa“criticalpath”均源自CMPBothassumeunlimited（unconstrained）resources均假定无限资源PERTprovidesforstatisticalanalysisofprojectdurations采用统计学方法进行项目历时分析,2011春夏学期授课版,6,PERT计划评审技术,ProgramEvaluationandReviewTechniqueBasedonideathatestimatesareuncertain基于不确定的估算Thereforeusesdurationranges历时范围Andtheprobabilityoffallingtoagivenrange以及概率方法Usesan“expectedvalue”（orweightedaverage）todeterminedurations使用“预期值”确定项目历时Usethefollowingmethodstocalculatetheexpecteddurations,thenuseasinputtoyournetworkdiagram,2011春夏学期授课版,7,PERT:

@#@NothingisCertain,SimilaritytoCPMmethodApproachtoactivitydurationestimationRoleofthecriticalpathProjectdurationstochasticUseoftheCLTtoassumenormalityDeterminingmeanandvarianceCalculatingP（projectdurationX）Underlyingassumptions将关键路径法应用于加权平均历时估算,2011春夏学期授课版,8,PERT的具体方法,Startwith3estimatesOptimistic乐观的估算Wouldlikelyoccur1timein20Mostlikely最可能的估算ModalvalueofthedistributionPessimistic悲观的估算Wouldbeexceededonlyonetimein20,2011春夏学期授课版,9,PERTFormula公式,Combinedtoestimateataskduration项目历时的加权平均期望值：

@#@,2011春夏学期授课版,10,PERTFormula,ConfidenceIntervalcanbedetermined如果每一分解的活动项能够被确定Basedonastandarddeviationoftheexpectedtime基于正态分布的标准偏差期望值：

@#@Usingabellcurve（normaldistribution）Forthewholecriticalpathuse用于CPM：

@#@,AnalysisofthePERTNetwork-EXAMPLE,2011春夏学期授课版,12,PERTAnalysisExample,Willdemonstrateconceptsusingexample,2011春夏学期授课版,13,PERTCPathVariance,IFYOUASSUMEINDEPENDENCEthevarianceofanypath=sumofactivityvariancesforallactivitiesonthatpathNORMALLYDISTRIBUTEDVarianceofthePROJECT=varianceoftheCRITICALPATHIfmorethanonecriticalpath,PROJECTVARIANCE=largestofCRITICALPATHVARIANCES,2011春夏学期授课版,14,PERTVariance,SinceNORMALLYDISTRIBUTEDcanestimateprobabilityofcompletingprojectontimecanestimateprobabilityofcompletingprojectbyanytargetdateifcriticalpathexpected=64,STDDEV=6Target=70Z=（70-64）/6=1probability=1-.84=.16,2011春夏学期授课版,15,PERTEstimates,Sowhatdoyoumeanbyoptimistic,pessimistic?

@#@valueyouexpecttobeexceededataprobabilitylevelandnotexceededat1-aprobabilityPROBLEM:

@#@estimatingtheMOSTLIKELYdurationofmostthingsishardAskingestimatorstocomeupwith“Whatwontbeexceeded95%ofthetime”isaguessatbest.,2011春夏学期授课版,16,PERT,Advantages优势Accountsforuncertainty试图将风险与历时联系起来Disadvantages劣势Timeandlaborintensive耗费的时间和工作量大风险评估还有更好的方法实践中其实使用不多Mostlyonlyusedonlarge,complexproject只被用于大的、复杂的项目GetPERTsoftwaretocalculateitforyou,IssuesinNetworkScheduling,2011春夏学期授课版,18,ProjectSchedulingIssues,Atypicalprojecthaslessthan10%ofactivitieswhichareidentifiedascriticalPointvs.probabilisticestimates项目进度安排被认为是，有至少10的活动存在严重的问题。

@#@因此，许多项目实际上存在很多不切实际的进度预期。

@#@,2011春夏学期授课版,19,ProjectSchedulingIssues,CPMorPERT:

@#@ResearchonPERT/CPMprojectsTechnicalperformance-Nosignificantdifference技术上无重大差异Probabilityofcost&@#@scheduleoverruns-Significantdifference在成本和进度估算上有重大差异Adequacyofestimates&@#@WBSUnconstrainedresources,2011春夏学期授课版,20,ReducingProjectDuration减少项目历时,Howcanyoushortentheschedule?

@#@Via缩短项目历时的方法Reducingscope（orquality）减小项目范围或品质Addingresources增加资源Concurrency（performtasksinparallel）并发Substitutionofactivities分包,2011春夏学期授课版,21,CompressionTechniques压缩的方法,Shortentheoveralldurationoftheproject缩短项目全部历时CrashingLooksatcostandscheduletradeoffs关注成本和进度的权衡Gaingreatestcompressionwithleastcost压缩最小成本Addresourcestocriticalpathtasks给关键路径增加资源Limitorreducerequirements（scope）减少或限定必要条件（如范围）Changingthesequenceoftasks改变任务次序FastTrackingOverlappingofphases,activitiesortasksthatwouldotherwisebesequential将连续有序的阶段、活动或任务重叠Involvessomerisk陷入风险Maycauserework导致返工,PrecedenceDiagrammingMethod（PDM）前导图法,2011春夏学期授课版,23,PrecedenceDiagrammingMethod前导图法,ExtensionofbasicPERT/CPM方法的延伸PermitspartialparallelperformanceofmutuallydependentactivitiesAllowanceof“overlap”ofactivities-notjustserialBetterrecognitionof“realworld”relationshipsbetweenactivities一种用方框代表活动的网络制图技术，对加强特定类型时间关系的可视性很有帮助,2011春夏学期授课版,24,PrecedenceDiagrammingMethod前导图法,Usedby“virtuallyall”projectmanagementsoftware实质上被用于几乎全部的项目管理软件MorepopularthanCPM/PERTmethod比CPM/PERT法流行AllowsmoreflexibilitythanCPM/PERTinlead/lagrelationshipsdifferenttypesofdependencies比CPM/PERT法在依赖关系方面更有弹性,2011春夏学期授课版,25,PDMActivityonNodeNotationPDM活动节点符号,2011春夏学期授课