Preferences消费者偏好(2)知识讲解.ppt

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1、Preferences消费者偏好(2)WhatDoWeMeanbyPreference?(偏好)Itreferstotheorderedrelationshipamongalternativechoicesgivenbyaneconomicagent.Inmosteconomicliterature,consumerpreferenceistreatedastheultimateexogenouselement.PreferenceRelationsComparingtwodifferentconsumptionbundles,xandy:strictpref

2、erence:xismorepreferredthanisy.weakpreference:xisasatleastaspreferredasisy.Indifference:xisexactlyaspreferredasisy.Notationsdenotesstrictpreference;~denotesindifference;denotesweakpreference;p~fPreferenceRelationsxyandyximplyx~y.xyand(notyx)implyxy.~f~f~f~fpAssumptionsaboutPreferenc

3、eRelationsCompleteness:Foranytwobundlesxandyitisalwayspossibletomakethestatementthateitherxyoryx.~f~fAssumptionsaboutPreferenceRelationsReflexivity:Anybundlexisalwaysatleastaspreferredasitself;i.e.xx.~fAssumptionsaboutPreferenceRelationsTransitivity:Ifxisatleastaspreferredasy,an

4、dyisatleastaspreferredasz,thenxisatleastaspreferredasz;i.e.xyandyzxz.~f~f~fIndifferenceCurves无差异曲线(或,无差异集)Takeareferencebundlex’.Thesetofallbundlesequallypreferredtox’istheindifferencecurvecontainingx’;thesetofallbundlesy~x’.Sinceanindifference“curve”isnotalwaysacurveabetternamemi

5、ghtbeanindifference“set”.IndifferenceCurvesx2x1x”x”’x’~x”~x”’x’IndifferenceCurvesx2x1zxyppxyzIndifferenceCurvesx2x1xAllbundlesinI1arestrictlypreferredtoallinI2.yzAllbundlesinI2arestrictlypreferredtoallinI3.I1I2I3IndifferenceCurvesx2x1WP(x),thesetofbundlesweaklypreferredtox.WP(x)i

6、ncludesI(x).xI(x)IndifferenceCurvesx2x1SP(x),thesetofbundlesstrictlypreferredtox,doesnotincludeI(x).xI(x)IndifferenceCurvesCannotIntersect!(不相交!)x2x1xyzI1I2FromI1,x~y.FromI2,x~z.Thereforey~z.IndifferenceCurvesCannotIntersectx2x1xyzI1I2FromI1,x~y.FromI2,x~z.Thereforey~z.ButfromI1

7、andI2weseeyz,acontradiction.pSlopesofIndifferenceCurvesWhenmoreofacommodityisalwayspreferred,thecommodityisagood.Ifeverycommodityisagoodthenindifferencecurvesarenegativelysloped.SlopesofIndifferenceCurvesBetterWorseGood2Good1Twogoodsanegativelyslopedindifferencecurve.SlopesofIndif

8、ferenceCurvesIfless