北京大学中级微观经济学课件ch14

北京大学中级微观经济学课件范里安微观经济学现代观点

Chapter FourteenConsumer’s Surplus 消费者剩余

北京大学中级微观经济学课件范里安微观经济学现代观点

Structure Money

equivalent of utility gains to

trade Consumer’s surplus Changes in consumer’s surplus Compensating and equivalent variations Producer’s surplus

北京大学中级微观经济学课件范里安微观经济学现代观点

Monetary Measures of Gains-toTrade You

can buy as much gasoline as you wish at $1 per gallon once you enter the gasoline market. Q: What is the most you would pay to enter the market? A: You would pay up to the dollar value of the gains-to-trade you would enjoy once in the market.

北京大学中级微观经济学课件范里安微观经济学现代观点

Monetary Measures of Gains-toTrade How

can such gains-to-trade be measured? Three such measures are: Consumer’s Surplus Equivalent Variation (等价变换), and Compensating Variation (补偿变换). Only in one special circumstance do these three measures coincide.

北京大学中级微观经济学课件范里安微观经济学现代观点

Reservation Price Maximum

willingness to pay for an additional unit of a good Two goods: good 1 (x1) and expenditure on others (x2); p2=1 By budget constraint (p1x1+x2=m): If x1=0, then x2=m If x1=1, then x2=m-p1 If x1=2, then x2=m-2p1 If x1=3, then x2=m-3p1

北京大学中级微观经济学课件范里安微观经济学现代观点

Reservation Price Reservation

price for the 1st unit (r1) u(0, m) = u(1, m-r1) r1 is the dollar equivalent of the marginal utility of the 1st unit. Reservation price for the 2nd unit (r2) u(1, m-r2) = u(2, m-2r2) r2 is the dollar equivalent of the marginal utility of the 2nd unit. Reservation price for the 3rd unit (r3) u(2, m-2r3) = u(2, m-3r3)

北京大学中级微观经济学课件范里安微观经济学现代观点

$ Equivalent Utility Gains Generally,

if she already has n-1 gallons of gasoline then rn denotes the most she will pay for an nth gallon. rn is the dollar equivalent of the marginal utility of the nth gallon.

北京大学中级微观经济学课件范里安微观经济学现代观点

$ Equivalent Utility Gains r1

+ … + rn will be the dollar equivalent of the total change to utility from consuming n gallons of gasoline at a price of $0.

北京大学中级微观经济学课件范里安微观经济学现代观点

$ Equivalent Utility Gains($) Res. Values

Reservation Price Curve for Gasoline

r1 10 8 r2 r3 6 4 r4 2 r5 0 r6

1

2

3

4

5

6

Gasoline (gallons)

北京大学中级微观经济学课件范里安微观经济学现代观点

$ Equivalent Utility Gains What

is the monetary value of our consumer’s gain-to-trading in the gasoline market at a price of $pG?

北京大学中级微观经济学课件范里安微观经济学现代观点

$ Equivalent Utility Gains The

dollar equivalent net utility gain for the 1st gallon is $(r1 - pG) and is $(r2 - pG) for the 2nd gallon, and so on, so the dollar value of the gain-to-trade is $(r1 - pG) + $(r2 - pG) + … for as long as rn - pG > 0.

北京大学中级微观经济学课件范里安微观经济学现代观点

$ Equivalent Utility Gains So

r1 + … + rn - pGn will be the dollar equivalent of the total change to utility from consuming n gallons of gasoline at a price of $pG each.

北京大学中级微观经济学课件范里安微观经济学现代观点

$ Equivalent Utility Gains($) Res. Values

Reservation Price Curve for Gasoline

r1 10 8 r2 r3 6 4 r4 2 r5 0 r6

pG

1

2

3

4

5

6

Gasoline (gallons)

北京大学中级微观经济学课件范里安微观经济学现代观点

$ Equivalent Utility Gains($) Res. Values

Reservation Price Curve for Gasoline

r1 10 8 r2 r3 6 4 r4 2 r5 0 r6

pG

1

2

3

4

5

6

Gasoline (gallons)

北京大学中级微观经济学课件范里安微观经济学现代观点

$ Equivalent Utility Gains($) Res. Values 10 r1 r2 8 r3 6 r4 4 r5 2 r6 0

Reservation Price Curve for Gasoline

$ value of net utility gains-to-trade

pG

1

2

3

4

5

6

Gasoline (gallons)

北京大学中级微观经济学课件范里安微观经济学现代观点

$ Equivalent Utility Gains If

gasoline can be purchased in any quantity then ...