2. Applying OLS to the reduced form of the model, get the OLS estimators of the reduced form model 3. According to the relationship between the parameters of the reduced form model and the parameters of the original model, obtain the estimators of the original parameters these estimators are the indirect least squares estimators A B 11+2 1+A2. Applying OLS to the reduced form of the model, get the OLS estimators of the reduced form model. 3.According to the relationship between the parameters of the reduced form model and the parameters of the original model, obtain the estimators of the original parameters, these estimators are the indirect least squares estimators. 2 1 1 1 A A B + = 2 2 2 1 A A B + =