城市經(jīng)濟(jì)學(xué)課件：Crime

Crime

IntroductiontoCrimeEconomicapproach:CriminalsrespondtoincentivesCrimereducedbytraditionalcrime-fightingresources(police,prisons)Crimereducedbyincreasingreturnstolawfulactivities(schools)13-213-313-413-5TheRationalCriminalEconomicsofdoubleparking50-50chanceofgaining$44orlosing$36Whowilltaketherisk?Peoplegenerallyriskaverse:Needmorethan+$44tooffsetriskof-$36Peopledifferinaversiontoanti-socialactions--anguishcost13-613-713-8PreventingCrimeIncreaseprobabilityofprison(probabilityoffailure)to0.75Lengthenprisontermto0.51:Decreasefailureutilityto7utilsDecreasethelootto$21:Decreasesuccessutilityto11utils13-9IncomeandCrime:Column5inTable13-3Income=$400;lawfulutility=20utilsHigh-income:SamelootbutfourtimestheopportunitycostEU(crime)=18.5utils=0.50?U(444)+0.50?U(256)Implication:Lowercrimeamonghigh-incomepeople13-10Morality&AnguishCosts:Column6ofTable13-3Mostpeopleaversetocommittinganti-socialactslikecrimeLowprobabilityofprison=0.25EU(crime)=11utils=0.75?U(144)+0.25?U(64)EU(crime)>Lawfulutility,socommitcrimeIfanguishcost=2utils,expectedutilityofcrime=9utils<Lawfulutility13-1113-1213-13EmpiricalEvidence:CrimeSupplyElasticitiesElasticityofsupplyw.r.t.Probabilityofprison=-0.30Elasticityofsupplyw.r.t.Arrestratio=-0.30Elasticityofsupplyw.r.t.Numberofpolice=-0.40to-0.5013-14IncreasingtheSeverityofPunishmentLongerprisontermincreasescrimecost,shiftingMC(supply)curveupwardElasticityclosetozeroLongerprisontermcausesoffsettingchangesHardencriminal:loweranguishcostshiftsMC(supply)shiftsdownwardPrisonschooling:skillacquisitionshiftsMC(supply)downward13-15EducationandCrimeEducationincreaseswages,decreasingcrimeCollegewagepremium=100%High-schoolgraduationwagepremium=50%13-16LawfulOpportunitiesandCrimeStudiesoflinkbetweenunemploymentrateandcrimeWeakrelationshipbetweencrimeandoverallunemploymentrateTeenagecrime(first-timeoffenders)sensitivetounemploymentrateStudiesoflinkbetweenlawfulwagesandcrimeIncreaseinlawfulwageincreasesopportunitycost,shiftingMC(supply)upwardLow-skilledworkers:Elasticity(crime,wage)between-1.0and-2.0Improvingjobprospectsforlow-skilledworkersreducescrime13-17Education-CrimeLinkforHigh-SchoolEducationAdditionalyearofHSdecreasescrimeparticipationrate:Reductionof0.10percentagepointsforwhites;0.40pctpointsforblacksGraduationdecreasescrimeparticipationratesofwhitemales:9%forviolentcrime;5%fordrugcrime;10%forpropertycrimeElasticity(Arrestrate,Graduationrate)=-2.0(violent)and-1.30(motorvehicle)EffectsofpreventingadropoutCostperyearofschooling=$6,000Reductionincrime=$1,600peryearforrestofwork/crimelife13-18WhyMoreCrimeinBigCities?Elasticityofcrimeratewithrespecttosize=0.15Moreloot(25%ofdifference)Lowerprobabilityofarrest(15%ofdifference):Table13-4Morefemale-headedhouseholds(50%ofdifference)13-1913-2013-2113-22RoleofLegalizedAbortionCrimerateshigheramongchildrenborntoreluctantparentsAbortiondecreasednumberofunwantedbirthsAvailabilityofabortionin1970sreducedthenumberofpeoplematuringincrime-proneyearsin1990s--afavorabledemographicchangeCutcrimerateby10%;responsibleforonethirdofcrimedropCaution:Otherstudiesshowsmallereffect13-23TheOptimalAmountofCrimeHowmuchcrimeshouldwechoose?VictimCostsIncludescostsofinjury,recoverytime,lostpropertyEstimatedcostpervictim:$370(larceny),$1,500(burglary),$4,000(autotheft),$13,000(armedrobbery),$15,000(assault)Aresomecrimeslessexpensivetoexperiencethantoprevent?13-2413-25CrimeSubstitutionandMarginalDeterrenceCriminalshaveoptions,andalternativecrimesaresubstitutesEquilibrium:EqualnetreturnfordifferentcrimesChangeincostofonecrimecausessubstitutiontowardothercrimes13-2613-27ImplicationsfortheSocialCostofCrimeVictimcostofrobberyis8.7timesthecostofburglaryBreakeveninsocialcost:8.7fewerburglariesoffseteachadditionalrobberyExampleinFigure13-9:3fewerburglariesforeachadditionalrobbery13-28ShouldthePunishmentFittheCrime?PenaltyforburglarylessthanpenaltyforarmedrobberyPolicyobjective:Developpenaltymenutogenerateoptimumcrimemix13-29PrisonsandCrimeOverallelasticityofcrimew.r.t.prisonpopulation:Propertycrime:-0.25Violentcrime:-0.40Effectsoncrime:deterrence,incapacitation,rehabilitationDeterrence:increaseincertaintymoreeffectivethanincreaseinseverity13-30Prisons:IncapacitationTakecriminalsoutofcirculationMixedresults:eachprisonerwouldhavecommitted0-17crimesMarginalbenefitsandcostsofincarcerationMarginalbenefit=$15,000inavoidedcrimeExcludesbenefitsofreducedfearandprotectivemeasuresMarginalcost=$36,000infacilitycostandopportunitycost13-31Prisons:RehabilitationProvidecriminalswithskillsrequiredforsuccessinlawfulemploymentTwothirdsparticipateinrehabilitationprograms,broadlydefinedSimplefactarenotencouragingRoughly2/3offormerinmatesrearrestedwithin3yearsofreleaseReleasedinmatesaccountfor10%-12%ofcrime