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Full-Text Articles in Social and Behavioral Sciences
Local Identification Of Nonparametric And Semiparametric Models, Xiaohong Chen, Victor Chernozhukov, Sokbae Lee, Whitney Newey
Local Identification Of Nonparametric And Semiparametric Models, Xiaohong Chen, Victor Chernozhukov, Sokbae Lee, Whitney Newey
Cowles Foundation Discussion Papers
In parametric models a sufficient condition for local identification is that the vector of moment conditions is differentiable at the true parameter with full rank derivative matrix. 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, single-index IV models, and semiparametric consumption-based asset pricing models.
Local Identification Of Nonparametric And Semiparametric Models, Xiaohong Chen, Victor Chernozhukov, Sokbae Lee, Whitney Newey
Local Identification Of Nonparametric And Semiparametric Models, Xiaohong Chen, Victor Chernozhukov, Sokbae Lee, Whitney Newey
Cowles Foundation Discussion Papers
In parametric models a sufficient condition for local identification is that the vector of moment conditions is differentiable at the true parameter with full rank derivative matrix. We show that there are corresponding sufficient conditions for nonparametric models. A nonparametric rank condition and differentiability of the moment conditions with respect to a certain norm imply local identification. It turns out these conditions are slightly stronger than needed and are hard to check, so we provide weaker and more primitive conditions. We extend the results to semiparametric models. We illustrate the sufficient conditions with endogenous quantile and single index examples. We …
A Simple Test For Identification In Gmm Under Conditional Moment Restrictions, Francesco Bravo, Juan Carlos Escanciano, Taisuke Otsu
A Simple Test For Identification In Gmm Under Conditional Moment Restrictions, Francesco Bravo, Juan Carlos Escanciano, Taisuke Otsu
Cowles Foundation Discussion Papers
This paper proposes a simple, fairly general, test for global identification of unconditional moment restrictions implied from point-identified conditional moment restrictions. The test is based on the Hausdorff distance between an estimator that is consistent even under global identification failure of the unconditional moment restrictions, and an estimator of the identified set of the unconditional moment restrictions. The proposed test has a chi-squared limiting distribution and is also able to detect weak identification alternatives. Some Monte Carlo experiments show that the proposed test has competitive finite sample properties already for moderate sample sizes.