(卫生经济学课件)CBA

1Cost-benefitanalysis•ConceptofCBA•Measureofbenefits•Cost-benefitanalysis2ConceptofCBA•CBAcomparesthediscountedfuturestreamsofprogrambenefitswithprogramcosts.•ThegoalofCBAistoidentifywhethertheaprogram’sbenefitsexceeditscosts.•Apositivenetsocialbenefitindicatesaprogramisworthwhile.•InCBA,programconsequencesarevaluedinmonetaryunits,becomingbenefits.3DifferencebetweenCBAandCEA/CUA•CBAisbroaderinscopethanCEA/CUA–cancompareprogramswithinandbetweensectorsoftheeconomytoinformresourceallocationdecision–cantelliftheprogrammeisworthwhileornot,butCEA/CUAcannot–CEA/CUAaddressmainlyquestionsofproductionefficiency,incontrast,CBAaddressbothproductionefficiencyandallocativeefficiency6Humancapitalapproach(2)•Itplacesmonetaryweightsonhealthytimeusingmarketwageratesandthevalueoftheprogramisassessedintermsofthepresentvalueoffutureearnings.–Tovalueallaspectsofhealthimprovements–Tovaluepartofthebenefitsofhealthcareinterventions,usingearningsdataasameansofvaluingproductivitychangesonly.7Difficultiesofhumancapitalapproach•Intheorywageratesreflectthemarginalproductivityofaworker,butitmayreflectinequitiessuchasdiscriminationbyraceorgender.•Fromasocietalperspectivetheanalystwouldneedtoconsiderthevalueofhealthytimegainedthatisnotsoldforawage.–Shadowpriceonnon-marketedresources:•opportunitycostoftime•areplacementcost8Revealedpreferenceapproach•Toexaminetherelationshipbetweenparticularhealthrisksassociatedwithahazardousjobandwageratesthatindividualsrequiretoacceptthejob.•Thestrengthisthatitisbasedonactualconsumerchoicesinvolvinghealthversusmoney,ratherthanhypotheticalscenariosandpreferencestatements.•Theweaknessisthatestimatedvalueshavevariedwidelyandestimationseemstobecontextandjob-specific.Inthereallife,thechoiceofjobisnotonlydependedontherisk.Manyfactorsconfoundtherelationshipbetweenwageandhealthrisk.9Exampleofrevealedpreference•SupposejobsAandBareidenticalexceptthatworkersinjobAhavehigherannualfatalinjuryriskssuchthat,onaverage,thereisonemorejob-relateddeathperyearforevery10,000workersinjobAthanjobB,andworkersinjobAearn$500moreperyearthanthoseinjobB.•Whatistheimpliedvalueofstatisticallife?10Answertotheexampleofrevealedpreference•Theimpliedvalueofstatisticallifeisthen$5millionforworkersinjobBwhoareeachwillingtoforgo$500peryearfora1/10,000lowerannualdeathrisk.•500x10,000=5,000,000=5million11Statedpreferenceapproach(WTP)•Tousesurveymethodstopresentrespondentswithhypotheticalscenariosabouttheprogramorproblemunderevaluation.Respondentsarerequiredtothinkaboutthescenariosandtorevealthemaximumtheywouldbewillingtopayfortheprogramorbenefit.•InmanywaysCBAstudiesbasedoncontingentvaluationandstatementofWTPcanbethoughtofasattemptstoreplacemissingmarkets,inanattempttomeasureunderlyingconsumerdemandandvaluationfornon-marketsocialgoods.12ExampleofWTPforroadsafety•Supposethatyouarebuyingaparticularmakeofcar.Youcan,ifyouwant,choosetohaveanewkindofsafetyfeaturefittedtothecaratanextracost.Thenextfewquestionswillaskabouthowmuchextrayouwouldbepreparedtopayforsomedifferenttypesofsafetyfeature.Youmustbearinmindhowmuchyoupersonallycanafford.Theriskofacardriverbeingkilledinanaccidentis10/100,000.Youcouldchoosetohaveasafetyfeaturefittedtoyourcarwhichwouldhavetheriskofthecardriverbeingkilled,downto5/100,000.Takingintoaccounthowmuchyoucanpersonallyafford,whatisthemostthatyouwouldbepreparedtopaytohavethissafetyfeaturefittedtothecar?13AnswertotheWTPexample•currentriskofdeathwithoutsafetyfeature=10/100,000•newriskwithsafetyfeature=5/100,000•reductioninrisk=5/100,000•maximumWTP=$50•impliedvalueoflife=50/5x10-5•=$1m14GlobalversusrestrictedWTP•Threebroadcategoriesofbenefits:intangible,futurehealthcarecostsavoidedandincreasedproductiveoutput.•RestrictedWTPonlyvaluethosecomponentofbenefitforwhichnomoneyvaluesexistedfromothermarketsources,thusonlyintangible(changeinhealth).•GlobalWTPvalueallthethreecategoriesofbenefits.15CommonmethodstoelicitWTP•Open-endedquestion•Biddinggame•Take-it-or-leave-it•Paymentcard16Advantagesanddisadvantages•Open-endedquestion•Biddinggame•Take-it-or-leave-it•Paymentcard17Cost-benefitanalysisnttiiirtctbNSB11)1()()(NSBi=netsocialbenefitofprojecti(discounted)bi(t)=benefits(inmoneyterms)derivedinyeartci(t)=costs(inmoneyterms)inyeart1/(1+r)=discountfactoratannualinterestratern=lifetimeofproject(years)18Reviewquestions•UnderstandingconceptofCBA•WhataretheusesofCBA•Classificationofbenefits•Methodstomeasurebenefits•Assumptionsofhumancapitalapproach•Howtocalculatetheimpliedvalueofstatisticallife•MethodstoelicitWTP,andtheiradvantagesanddisadvantages