Global Identification In Nonlinear Semiparametric Models

This note derives primitive conditions for global identification in nonlinear simultaneous equations systems. Identification is semiparametric in the sense that the latent structural disturbance is only known to satisfy a number of orthogonality restricitions with respect to observed instruments. Our contribution to the literature on identification in a semiparametric context is twofold. First, we derive a set of unconditional moment restrictions on the observables that are the starting point for identification in nonlinear structural systems. Second, we provide primitive conditions under which a parameter value that solves those restrictions is unique.