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Analogous Estimating

Analogousestimatingisatechniqueforestimatingthedurationorcostofanactivityoraproject
usinghistoricaldatafromasimilaractivityorproject.Analogousestimatingusesparametersfroma
previous,similarproject, suchasduration,budget,size, weight,andcomplexity,as thebasisfor
estimatingthesameparameterormeasureforafutureproject.Whenestimatingdurations,this
techniquereliesontheactualdurationofprevious,similarprojectsasthebasisforestimatingthe
durationof thecurrent project.Itis agross value-estimating approach,sometimes adjustedfor
known differences in project complexity. Analogous duration estimating is frequently used to
estimateprojectdurationwhenthereisalimitedamountofdetailedinformationabouttheproject.
Analogousestimatingisgenerallylesscostlyandlesstime-consumingthanothertechniques,butitis
alsolessaccurate.Analogousdurationestimatescanbeappliedtoatotalprojectortosegmentsofa
projectandmaybeusedinconjunctionwithotherestimatingmethods.Analogousestimatingismost
reliablewhenthepreviousactivitiesaresimilarinfactandnotjustinappearance,andtheproject
teammemberspreparingtheestimateshavetheneededexpertise.

92 .Answer:C.

PMBOK® Guide, pages 244 – 245 , Section 7. 2. 2. 5

Three-PointEstimating

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Depending on the assumeddistribution ofvalues within the range ofthe threeestimates, the
expectedduration,tE,canbecalculatedusingaformula.Twocommonlyusedformulasaretriangular
andbetadistributions.Theformulasare:

o Triangulardistribution.tE=(tO+tM+tP)/ 3

o Betadistribution(fromthetraditionalPERTtechnique).tE=(tO+ 4 tM+tP)/ 6

Durationestimatesbasedonthreepointswithanassumeddistributionprovideanexpectedduration
andclarifytherangeofuncertaintyaroundtheexpectedduration.

93 .Answer:B.

PMBOK® Guide, pages 244 – 245 , Section 7. 2. 2. 5

Three-PointEstimating

...

The accuracy of single-point duration estimates may be improved by considering estimation
uncertaintyandrisk.Usingthree-pointestimateshelpsdefineanapproximaterangeforanactivity's
duration:

o Mostlikely(tM).Thisestimateisbasedonthedurationoftheactivity,giventheresourceslikelyto
beassigned,theirproductivity,realisticexpectationsofavailabilityfortheactivity,dependencieson
otherparticipants,andinterruptions.

o Optimistic(tO).Theactivitydurationbasedonanalysisofthebest-casescenariofortheactivity.

o Pessimistic (tP). The duration based on analysis of the worst-case scenario for the activity.
Dependingontheassumeddistributionofvalueswithintherangeofthethreeestimates,the
expectedduration,tE,canbecalculated.Onecommonlyusedformulaistriangulardistribution:tE