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Question 15 1 pts Two Stage Least Squares is calculated as follows; in the first stage: O the exogenous variables are regressed on the instruments. The predicted value of the exogenous variables is then used in the second stage, together with the instruments, to predict the dependent variable. O the unknown coefficients in the reduced form equation are estimated by weighted least squares, and the predicted values are calculated. In the second stage, Y is regressed on these predicted values and the other exogenous variables. OY is regressed on the exogenous variables only. The predicted value of Y is then regressed on the instrumental variables. O Y is regressed on the exogenous variables only. The predicted value of Y is then regressed on the instrumental variables