第一讲-消费者行为理论(2)偏好.ppt

*Completeness:ForanytwobundlesxandyitisalwayspossibletomakethestatementthateitherorReflexivity:AnybundlexisalwaysatleastaspreferredasitselfTransitivity:If

xisatleastaspreferredasy,and

yisatleastaspreferredasz,then

xisatleastaspreferredasz;i.e.*偏好一般用无差异曲线来描述。Takeareferencebundlex’.Thesetofallbundlesequallypreferredtox’istheindifferencecurvecontainingx’;thesetofallbundlesy~x’.Sinceanindifference“curve”isnotalwaysacurveabetternamemightbeanindifference“set”.*单调性----对于正常商品，总是越多越好。AllbundlesinI1arestrictlypreferredtoallinI2.AllbundlesinI2arestrictlypreferredtoallinI3.*WP(x),thesetofbundlesweaklypreferredtox.*I1和I2是两条代表不同满足水平的无差异曲线，如果两条曲线相交于X点，而组合Y属于I1，组合Z属于I2。根据偏好关系的传递性得到y~z，这与Y和Z在不同的无差异曲线上，具有不同满足水平矛盾。*完全替代的产品在现实生活中并不多见，严格说来，上例中的两种面额货币并不是严格的完全替代品，特别是当数额较大时，消费者携带10元面额的货币更加方便。无差异曲线的斜率反映了两种商品替换的比例。onlythenumberofpairsofunitsofthetwocommoditiesdeterminesthepreferencerank-orderofbundles.*Sinceeachof(5,5),(5,9)and(9,5)contains5pairs,eachislesspreferredthanthebundle(9,9)whichcontains9pairs.由于完全互补品的严格互补性，它们往往被同一个生产者在同一时间内进行生产，而且被在同一地点进行销售。*Acommodityisinfinitelydivisibleifitcanbeacquiredinanyquantity;e.g.waterorcheese.Acommodityisdiscreteifitcomesinunitlumpsof1,2,3,…andsoon;e.g.aircraft,shipsandrefrigerators.Supposecommodity2isaninfinitelydivisiblegood(gasoline)whilecommodity1isadiscretegood(aircraft).Whatdoindifference“curves”looklike?**Preferencesarestrictlyconvexwhenallmixtureszarestrictlypreferredtotheircomponentbundlesxandyforall0t1.*Themixturezislesspreferredthanxory.*MRSalwaysincreaseswithx1(becomeslessnegative)ifandonlyifpreferencesarestrictlyconvex.MRSdecreases(becomesmorenegative)asx1increasesnonconvexpreferences*《中级经济学》第一讲消费