Appendix A. the Structural PVAR Model the Structural PVAR Model Analyzing the Dynamics Among Structure (S), Pollution (P), Income (E) and Health (H) Is
Appendix A. The structural PVAR model The structural PVAR model analyzing the dynamics among structure (S), pollution (P), income (E) and health (H) is , , , , ,11 ,12 ,13 ,14 = − + + (A.1) , , , , ⎛ 21 22 23 24⎞ − ⎛ ⎞ ⎛ ⎞ =1 � � ∑ , , , , � − � ⎜ 31 32 33 34⎟ ⎜ ⎟ ⎜⎟ − 41 42 43 44 Define = ( ,⎝ , , ) , using matrix,⎠ Eq. (A.1) can⎝ be⎠ rewritten⎝ ⎠ as = ′ + + (A.2) The 4×4 matrix = ∑= 1reflects− the contemporaneous relation of the �� variables in , and = , are the coefficients of the lagged endogenous variables. Because both contemporaneous � � and long-run relationships are accounted for, we assume that the structural shock is homoskedastic, that is ~( , ), = ⎛ ⎞ ⎜ ⎟ ⎝ ⎠ To estimate eq. (A.2), transform Eq. (A.1) into the reduced form = + + , ~( , ) (A.3) where ∑=1 − = , = , = . Since matrix A is of full −rank, the covariance− matrix− Ω is no longer diagonal. In fact, we have = ( ) (A.4) To recover the structural− parameters− ′ in and , we must impose additional restrictions a priori. Note that the left-hand side of Eq. (A.4) contains 10 coefficients, because is symmetric. But on the right-hand side of (A.2), the number of unknowns in and are 16 and 4, respectively. Therefore, to pin down and , we need 16 + 4 − 10 = 10 more restrictions. Applying Cholesky decomposition, we impose a lower triangular structure on 0 0 0 0 0 = 11 0 21 22 � 31 32 � 33 To finally identify and , we41 should42 either set = = = = 1, 43 44 or = = = = 1 . Based on these restrictions, the PVAR model is 11 22 33 44 transformed into a recursive system. To see the impacts of shocks, we transform Eq. (A.1) to = + (A.5) 1 = � − ∑ � where L is the lag operator.
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