Chapter11联立方程模型 Simultaneous Equation Models
Chapter 11 联立方程模型 Simultaneous Equation Models
o Simultaneous Equation Models Example(供给—需求模型) Demanding equation 2d=6o+bu,P+b2r Supplying equation Q=b tb 21 ptb P,te 20 221-1 2 Simultaneous equation model Od =b 10 +b,+brt Q=b20+b21P+b2P1+E2
⚫ Simultaneous Equation Models Example(供给—需求模型） Demanding equation: Supplying equation: Simultaneous equation model: Q b b P b Y d 10 11 12 1 = + + + Q b b P b P s 20 21 22 1 2 = + + + − 10 11 12 1 20 21 22 1 2 d s d s Q b b P b Y Q b b P b P Q Q − = + + + = + + + =
P价格,Y收入,Q、供给,Q需求 平衡方程:Q=O Variables的类型 1) Endogenous variable(内生变量,P,Q、Q) (2) Exogenous variable(外生变量,Y) (3) Predetermined variable(前定变量,Y,R) Equations (1)Behavior(structural)equations 2)Relation identities(Given)
P—价格，Y—收入，Qs—供给，Qd—需求 平衡方程： Variables的类型: (1) Endogenous variable(内生变量， P， Qs，Qd ) (2) Exogenous variable(外生变量, Y) (3) Predetermined variable(前定变量，Y，P-1 ) Equations: (1) Behavior (structural) equations (2) Relation identities (Given) Q Q d s =
Simultaneity bias(联立性偏误): Some endogenous variables are both dependent variables and independent variables at the same time and some endogenous variables are relevant to the error terms. So the ols method does not hold good. That is Simultaneity bias 内生变量与误差项相关
Simultaneity Bias(联立性偏误）: Some endogenous variables are both dependent variables and independent variables at the same time and some endogenous variables are relevant to the error terms. So the OLS method does not hold good. That is Simultaneity Bias. 内生变量与误差项相关
● Structural forn: Structural forms are models which describe the structural relations of economic variables The equations of a structural form are called the structural equations and the parameters are called the structural parameters In a structural form if the number of the endo genous variables is the same as the number of the equations the structural form is complete
⚫ Structural form: Structural forms are models which describe the structural relations of economic variables. The equations of a structural form are called the structural equations and the parameters are called the structural parameters. In a structural form, if the number of the endogenous variables is the same as the number of the equations, the structural form is complete