上财中级微观经济学课件Ch4utility.ppt

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1、ChapterFourUtility1UtilityStructureUtilityfunction(效用函数）DefinitionMonotonictransformation（单调转换）ExamplesofutilityfunctionsandtheirindifferencecurvesMarginalutility（边际效用）Marginalrateofsubstitution边际替代率MRSaftermonotonictransformation2UtilityUtilityFunctionsAutilityfunctionU(x)repres

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

3、n-minus.4UtilityUtilityFunctions&Indiff.CurvesConsiderthebundles(4,1),(2,3)and(2,2).Suppose(2,3)(4,1)~(2,2).Assigntothesebundlesanynumbersthatpreservethepreferenceordering;e.g.U(2,3)=6>U(4,1)=U(2,2)=4.Callthesenumbersutilitylevels.p5UtilityUtilityFunctions&Indiff.CurvesAnindiffer

4、encecurvecontainsequallypreferredbundles.Equalpreferencesameutilitylevel.Therefore,allbundlesinanindifferencecurvehavethesameutilitylevel.6UtilityUtilityFunctions&Indiff.CurvesSothebundles(4,1)and(2,2)areintheindiff.curvewithutilitylevelUº4Butthebundle(2,3)isintheindiff.curvewit

5、hutilitylevelUº6.Onanindifferencecurvediagram,thispreferenceinformationlooksasfollows:7UtilityUtilityFunctions&Indiff.CurvesUº6Uº4(2,3)(2,2)~(4,1)x1x2p8UtilityUtilityFunctions&Indiff.CurvesComparingmorebundleswillcreatealargercollectionofallindifferencecurvesandabetterdescription

6、oftheconsumer’spreferences.9UtilityUtilityFunctions&Indiff.CurvesUº6Uº4Uº2x1x210UtilityUtilityFunctions&Indiff.CurvesThecollectionofallindifferencecurvesforagivenpreferencerelationisanindifferencemap.Anindifferencemapisequivalenttoautilityfunction;eachistheother.11UtilityUtilityF

7、unctionsThereisnouniqueutilityfunctionrepresentationofapreferencerelation.SupposeU(x1,x2)=x1x2representsapreferencerelation.Againconsiderthebundles(4,1),(2,3)and(2,2).12UtilityUtilityFunctionsU(x1,x2)=x1x2,soU(2,3)=6>U(4,1)=U(2,2)=4;thatis,(2,3)(4,1)~(2,2).p13UtilityUtilityF

8、unctionsU(x1,x2)=x1x2(2,3)(4,1)~(2,2).De