中级微观经济学课件第7章重点.docx

中级微观经济学课件第7章重点.docx

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中级微观经济学课件第7章重点

ChapterSeven

RevealedPreference显现性偏好

WhatIstheQuestionofthe

Chapter?

•Supposeweobserveacollectionofaconsumer’schoices,canwediscoverhis/herpreference?

•Isthispossibleatall?

Ifso,underwhatconditionsisthispossible?

（Thisisthereversequestionoffindingtheoptimalchoice

Digression:

Sciencevs.

Engineering

（对比科学家思维与工程师思维•找问题与解问题的不同

–要对问题提问题

•务虚与务实的不同

•解释世界与改造世界的不同

–旁观者与参与者的不同

MaintainedAssumptionson

Preferences

•Preferences

–donotchangewhilethechoicedataare

gathered.

–arestrictlyconvex.

–aremonotonic.

DirectPreferenceRevelation•Supposethatthebundlex*ischosenwhenthebundleyisaffordable.Thenx*isrevealeddirectlyaspreferredtoy（otherwiseywouldhavebeenchosen.

DirectPreferenceRevelation•Thatxisrevealeddirectlyaspreferredtoywillbewrittenas

xy.

≺

D

TwoAxiomsofRevealed

Preference

•Toapplyrevealedpreferenceanalysis,choicesmustsatisfytwocriteria--theWeakandtheStrongAxiomsofRevealedPreference.

Preference（WARP•ChoicedatawhichviolatetheWARPareinconsistentwitheconomicrationality.•TheWARPisanecessaryconditionforapplyingeconomicrationalitytoexplainobservedchoices.

Preference（WARP•WhatchoicedataviolatetheWARP?

CheckingifDataViolatethe

WARP

•Aconsumermakesthefollowingchoices:

–Atprices（p1,p2=（$2,$2thechoicewas

（x1,x2=（10,1.

–At（p1,p2=（$2,$1thechoicewas（x1,x2=

（5,5.

–At（p1,p2=（$1,$2thechoicewas（x1,x2=

（5,4.

•IstheWARPviolatedbythesedata?

Preference

•WhatchoicedatawouldsatisfytheWARPbutviolatetheSARP?

Preference•Considerthefollowingdata:

A:

（p

1,p

2

p

3

=（1,3,10&（x

1

x

2

x

3

=（3,1,4

B:

（p

1,p

2

p

3

=（4,3,6&（x

1

x

2

x

3

=（2,5,3

C:

（p

1,p

2

p

3

=（1,1,5&（x

1

x

2

x

3

=（4,4,3

Preference

•ThattheobservedchoicedatasatisfytheSARPisaconditionnecessaryandsufficientfortheretobeawell-behavedpreferencerelationthat“rationalizes”thedata.

•Soour3datacannotberationalizedbyawell-behavedpreferencerelation.

RecoveringIndifferenceCurves•SupposewehavethechoicedatasatisfytheSARP.

•Thenwecandiscoverapproximatelywherearetheconsumer’sindifferencecurves.

•How?

RecoveringIndifferenceCurves•Supposeweobserve:

A:

（p

1,p

2

=（$1,$1&（x

1

x

2

=（15,15

B:

（p

1,p

2

=（$2,$1&（x

1

x

2

=（10,20

C:

（p

1,p

2

=（$1,$2&（x

1

x

2

=（20,10

D:

（p

1,p

2

=（$2,$5&（x

1

x

2

=（30,12

E:

（p

1,p

2

=（$5,$2&（x

1

x

2

=（12,30.

•WhereliestheindifferencecurvecontainingthebundleA=（15,15?

RecoveringIndifferenceCurves•Thetableshowingdirectpreferencerevelationsis:

RecoveringIndifferenceCurves•SincethechoicessatisfytheSARP,thereisawell-behavedpreferencerelationthat“rationalizes”thechoices.

RecoveringIndifferenceCurves•Now,whataboutthebundlesrevealedasmorepreferredthanA?

RecoveringIndifferenceCurves•NowwehaveupperandlowerboundsonwheretheindifferencecurvecontainingbundleAmaylie.