Local Identification of Nonparametric and Semiparametric Models

In parametric, nonlinear structural models, a classical sufficient condition for local identification, like Fisher (1966) and Rothenberg (1971), is that the vector of moment conditions is differentiable at the true parameter with full rank derivative matrix. We derive an analogous result for the non...

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Bibliographic Details
Main Authors: Chen, Xiaohong, Chernozhukov, Victor V., Lee, Sokbae, Newey, Whitney K.
Other Authors: Massachusetts Institute of Technology. Department of Economics
Format: Article
Language:en_US
Published: John Wiley & Sons, Inc/Econometric Society 2015
Online Access:http://hdl.handle.net/1721.1/96142
https://orcid.org/0000-0002-3250-6714
https://orcid.org/0000-0003-2699-4704
Description
Summary:In parametric, nonlinear structural models, a classical sufficient condition for local identification, like Fisher (1966) and Rothenberg (1971), is that the vector of moment conditions is differentiable at the true parameter with full rank derivative matrix. We derive an analogous result for the nonparametric, nonlinear structural models, establishing conditions under which an infinite dimensional analog of the full rank condition is sufficient for local identification. Importantly, we show that additional conditions are often needed in nonlinear, nonparametric models to avoid nonlinearities overwhelming linear effects. We give restrictions on a neighborhood of the true value that are sufficient for local identification. We apply these results to obtain new, primitive identification conditions in several important models, including nonseparable quantile instrumental variable (IV) models and semiparametric consumption-based asset pricing models.