Whydoweestimate?

ToplanasateamasanorganisationallowourcustomerstoplanToworkouthowmuchsomethingmightcost

toseewhetherwecanaffordittoseeifourcustomercanaffordit情趣內衣

Whatdopeopledowithourestimates?Howdoweestimate?Theconeofuncertainty TherevisedconeofuncertaintyWhywewillalwaysunderestimateHofstadter'sLaw"Italwaystakeslongerthanyouexpect,evenwhenyoutakeHofstadter'sLawintoaccount.“OptimismBiasPlanningFallacyCognitiveBiasingeneralTheunknownunknownsHowcanweestimateforthatwhichwedonotyetknow?“Mediocristan” Countingbeansinajar Heightofhumanbeings“Extremistan” Googlesearchresults Stockmarket SoftwaredevelopmentBlackSwansPriceofoilDotcombubbleCreditcrunchRealisingourdefinitionofdonewasnotreally“done”NotrealisingtherewouldbesomanydifficultieswithourhostingproviderTherealconeofuncertainty

(noassumptions)ScrumEstimatingandPlanningGeneralestimationT-shirtsizing(S,M,L,YGBK)Complexitypoints(1,2,3,5,8,13,100)Shouldneverestimatein“manhours”EstimatesmadebytheteamdoingtheworkAddrangeoferror(e.g.Coneofcomplexity)Assumesteamwillstaythesameandrequirementsdon’tchangeIfthesedochangethensodoourestimatesAgilemethodologiesdonotmakeusmorepredictableTeamsgetbetteratestimatingastheygobutonlyuptoapointnotnecessarilyanybetterthanifwe’dspentalotofeffortmakingfinegrainedestimatesmaybealotworsetobeginwithWorkingiterativelymakesusmoreabletorespondtouncertaintybutdoesnotmeanwebecomeanymorepredictableAdoseofrealityTeamschange,requirementschange,environmentschangeT-shirtsizingandstorypointsgetturnedintomanhoursPeoplemakecommitmentseitherexplicitlyorimplicitlyCustomerdoesn’tcareaboutassumptions,theywanttoknowwhenit’llbereadyExample1Sprint0:noestimate letsdosomeworkandfindoutourvelocitySprint1:3-5monthsSprint1:4-6monthsSprint2:4-7monthsSprint3:5-7months teamhasreallybeddedinbythispointandismakingbetter estimatesSprint4:6-7months Customermakessomeimplicitcommitmentsonprojectbeing deliveredin4months(allowingcontingencyof1month)Sprint5:6-10months Atthispointa“BlackSwan”eventoccurs–wefindoutthehostingenvironmentdoesnothaveInfoSeccompliance.Newcompliantkithastobespec’dandbuiltandallthesoftwarehastobemovedandtested.Example2Sprint0:noestimate letsdosomeworkandfindoutourvelocitySprint1:2-4monthsSprint1:3-7monthsSprint3:5-7months teamhasreallybeddedinbythispointandismakingbetter estimates However,theBAleavesass/he’sbeenofferedaloadofmoneyby GoogleSprint4:5-8months Customermakessomeimplicitcommitmentsonprojectbeing deliveredin4months(allowingcontingencyof1month) VelocitydropsasteamrealiseswhatacontributiontheBAmadeSprint5:6-10months VelocitydropsevenfurtherasnewBAhasnoideawhattheywere talkingabou