| In this work, we study a class of nonparametric/semiparametric structural models with endogeneity under a varying or partially varying coefficient representation for the regression function using instrumental variables. Under this representation, models are linear in the endogenous components with either unknown functional coefficients of the predetermined variables or constant coefficients.; To estimate the functional coefficients in a nonparametric functional coefficient model, we propose a nonparametric two-step estimator that uses local linear approximations in both steps. The first step is to estimate a vector of reduced forms of regression models and the second step is a local linear regression using the estimated reduced forms as regressors.; To efficiently estimate the parameters in the partially varying coefficient structural model, we first regard the constant coefficients as functional coefficients and then apply the above nonparametric two-step estimation procedure. The final estimators of those parameters are obtained by taking the average of all the estimates at each sample point. To estimate the functional coefficients, we simply use the partial residuals by removing the constant coefficients part and then apply the above proposed nonparametric two-step estimation procedure.; The large sample results including the consistency and asymptotic normality of all the proposed estimators of functional/constant coefficients for both nonparametric and semiparametric models are derived and more importantly, it is also demonstrated that the estimators of the parameters are n -consistent. Finally, both Monte Carlo simulation studies and an application are used to illustrate the performance of the finite sample properties. |
