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Econometrics Paper
A method of moments estimator for semiparametric index models
Bas Donkers and Marcia M Schafgans
July 2005
Paper No' EM/2005/493:
Full Paper (pdf)

JEL Classification: C14; C31; C52

Tags: semiparametric estimation; multiple index models; average derivative functionals; generalized methods of moments estimator; rank testing

We propose an easy to use derivative based two-step estimation procedure for semi-parametric index models. In the first step various functionals involving the derivatives of the unknown function are estimated using nonparametric kernel estimators. The functionals used provide moment conditions for the parameters of interest, which are used in the second step within a method-of-moments framework to estimate the parameters of interest. The estimator is shown to be root N consistent and asymptotically normal. We extend the procedure to multiple equation models. Our identification conditions and estimation framework provide natural tests for the number of indices in the model. In addition we discuss tests of separability, additivity, and linearity of the influence of the indices.