中微课件范里安版 Micro Ch4.ppt

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1、ChapterFourUtility效用WhatDoWeDoinThisChapter?Wecreateamathematicalmeasureofpreferenceinordertoadvanceouranalysis.UtilityFunctionsApreferencerelationthatiscomplete,reflexive,transitiveandcontinuouscanberepresentedbyacontinuousutilityfunction.UtilityFunctionsAutilityfunctionU(x)representsapreferen

2、cerelationifandonlyif:x’x”U(x’)>U(x”)x’x”U(x’)

3、vehavethesameutilitylevel.U(x1,x2)=Constantistheequationofanindifferencecurve.UtilityFunctions&Indiff.CurvesUº6Uº4(2,3)(2,2)~(4,1)x1x2pUtilityFunctions&Indiff.CurvesThecollectionofallindifferencecurvesforagivenpreferencerelationisanindifferencemap.Anindifferencemapisequivalenttoautilityfunction

4、;eachistheother.UtilityFunctionsIfUisautilityfunctionthatrepresentsapreferencerelationandfisastrictlyincreasingfunction,thenV=f(U)isalsoautilityfunctionrepresenting.~f~fGoods,BadsandNeutralsAgoodisacommodityunitwhichincreasesutility(givesamorepreferredbundle).Abadisacommodityunitwhichdecreases

5、utility(givesalesspreferredbundle).Aneutralisacommodityunitwhichdoesnotchangeutility(givesanequallypreferredbundle).Goods,BadsandNeutralsUtilityWaterx’UnitsofwateraregoodsUnitsofwaterarebadsAroundx’units,alittleextrawaterisaneutral.UtilityfunctionSomeOtherUtilityFunctionsandTheirIndifferen

6、ceCurvesInsteadofU(x1,x2)=x1x2considerV(x1,x2)=x1+x2.Whatdotheindifferencecurvesforthis“perfectsubstitution”utilityfunctionlooklike?PerfectSubstitutionIndifferenceCurves55991313x1x2x1+x2=5x1+x2=9x1+x2=13V(x1,x2)=x1+x2.PerfectSubstitutionIndifferenceCurves55991313x1x2x1+x2=5x1+x2=9x1+x2=13Al

7、larelinearandparallel.V(x1,x2)=x1+x2.SomeOtherUtilityFunctionsandTheirIndifferenceCurvesInsteadofU(x1,x2)=x1x2orV(x1,x2)=x1+x2,considerW(x1,x2)=min{x1,x2}.Whatdotheindifferencecurvesforthis“perfectcomplementarity”utilityfunct