Document Type
Discussion Paper
Publication Date
11-1-2018
CFDP Number
2158
CFDP Pages
66
Journal of Economic Literature (JEL) Code(s)
C10, C52
Abstract
We consider inference in models defined by approximate moment conditions. We show that near-optimal confidence intervals (CIs) can be formed by taking a generalized method of moments (GMM) estimator, and adding and subtracting the standard error times a critical value that takes into account the potential bias from misspecification of the moment conditions. In order to optimize performance under potential misspecification, the weighting matrix for this GMM estimator takes into account this potential bias, and therefore differs from the one that is optimal under correct specification. To formally show the near-optimality of these CIs, we develop asymptotic efficiency bounds for inference in the locally misspecified GMM setting. These bounds may be of independent interest, due to their implications for the possibility of using moment selection procedures when conducting inference in moment condition models. We apply our methods in an empirical application to automobile demand, and show that adjusting the weighting matrix can shrink the CIs by a factor of 3 or more.
Recommended Citation
Armstrong, Timothy B. and Kolesár, Michal, "Sensitivity Analysis using Approximate Moment Condition Models" (2018). Cowles Foundation Discussion Papers. 107.
https://elischolar.library.yale.edu/cowles-discussion-paper-series/107
Supplemental material
Comments
Supplement Materials, 14 pp