村级一般均衡模型（GAMS 软件）

CGE model

宏观政策的微观影响

1.      Transformation of economicsmodel

Hand book of development economics, PeterTimmet

		Agricultural growth
		Low	Medium	High
Per-capita income growth	Low	most		Few
	Medium		most
	High	Few		most

Policy support growth

Policy makers: misunderstand

Survey questions? Details?

Good theory and good data

Good theory: assumptions-> tabledesign->data collection

So begin with theory: micro-rural economics

Theory: empirical

Do theory experiments

Household model and village model are thesame things, from the smaller to higher one.

Good models are: realistic but simple; estimable;useful for policy.

Capture most important features: simple butinclude most important things.

Real theories:

Price -> supply (positive)

Estimate how must …….

For purpose of quantitative。

You know the effects, you also want to knowhow much.

Assumption didn’t work.

Assuming perfect market, but the market isimperfect.

New classical market models. When thedemand-price curve is upward, why?

What is agriculture?

1.      Dispersed, there are manyagents.

Can’t reach them individually,  key inputs is land, transaction cost

Reach them individually

Model and behavior

Market sending in information

Stream important in agriculture.

If market is not perfect, first is toactivate market, it needs policy and both.

2.      Agri. Households (householdfarm)

Production and consumption

3.      Nature as input

4.      Timing, seasons, market arecritical

5.      Rural economics are increasingdiverse. Model of today includes risk analysis

6.      Need money at the beginning ofthe season, so credit is important.

Mexico, most important agricultural bank, migrants, some ofthe insurances

Chayanov: household economy, relationship betweenproduction and consumption, subsistence economy in Russia.

Family is young: hard working and little leisure.

Children growth, children can’t work, parents have a rest.

Perfectly interpreted.

Strauss: perfect markets

Utility function: U=U(Xa, Xm, Xl)

Xm, pure market goods, households doesn’t produce.

a, agricultural goods, households consumes and products

objective function: max U(Xa, Xm, Xl), s.t.: constraints ∑(pixi)=y， consumermodel y is fixed

today model: assumptions, y is endogenous on production,but p is fixed.

Y: full income, not cash income

1.      Cash income constraints

PmXm=cash income constraints=Pu(Q-Xa)-w(L-F)

Q-Xa=market surplus

wF: F is family labor input

WL: L is total labor input

In china, L-F≈0

2.      Family time constraints

Xl+F=T, F=T-Xl

3.      Production technologyconstraints

Q=Q(L,A), A=fixed capital land,                              

Combine constraints 1 to 3,PmXm+PaXa+wXl=wT+π

π=PaQ(L,a)-Wl

full expenditures=full income=y

so core of all the studies of agriculturalhouseholds is:

max: U(Xa, Xm, Xl)

s.t.: PmXm+PaXa+wXl=wT+π

add 2 lat constraints:

, 对于任意的i, i=a, m, l, Pl=w

Above variables are short term.

Technology: pay for it (buy tech.),irrigation system

Max Xa, Xl, Xm

采用拉格朗日乘数法：

     shadow price

FOC.

Perfect market is important, the model isrecursive.

Solve production from consumption side.

-> -> -> -> =BUDGET CONSTRAINT

,  ,  

, give y*, we have y equation,

,  , to solve model.

Find L*, Q*, π*, Y*

Find xa*(Pa,Pm,w,y*), xm*(Pa,Pm,w,y*), xl*(Pa,Pm,w,y*)

MS*=Q*-Xa*,  , H*=L*-F*

  

The first park of the equation is sluskysubstitution.

Q(L, A)=C D function=

, this is a linear demand.

Attention:  ;        ;  

,  ,  

Max U

s.t. PmXm+PaXa+wXl=y*

Xa=β1y*, Xm=β2y*, Xl=β3y*,

Xa=β1y/Pa, Xm=β2y/Pm, Xl=β3y/Pl,

CD demand: Xa=β1y*/Pa, β1=PaXa/Y*

边际增长=平均+增长

Engel’s law is abbreviated