4. Simultaneous Equation Model Consider the following structural system of equations (in deviations form): y1i=1y2i+1x1i+2x2i+u1iy2i=2y1i+3x1i+4x2i+u2i Where Y1 and Y2 are endogenous variables, X1 and X2 are exogenous variables, and u1 and u2 are uncorrelated with each other. 1 and 2 are the structural parameters of interest. a. (2 points) State the order condition for an equation to be identified. b. (3 points) Discuss the identifiability of the structural parameters using the condition for identification for each of the following cases: i. No restriction on 's. ii. 1=4=0. iii. 1=2=3=0. c. (2 points) For case (iii) in (b), can the reduced form equations be used to identify any of the parameters of the structural equations? Which one(s)? [Hint: Write out the reduced form equation.] d. (3 points) Suppose you run two regressions for case (iii) in (b) y1=0+1x2+1y2=0+1x2+2 What does 1/1 estimate? What is the name of this estimator