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Title: Weak Instruments in Instrumental Variables Regression: Theory and Practice
When instruments are weakly correlated with endogenous regressors, conventional methods for instrumental variables (IV) estimation and inference become unreliable. A large literature in econometrics has developed procedures for detecting weak instruments and constructing robust confidence sets, but many of the results in this literature are limited to settings with independent and homoskedastic data, while data encountered in practice frequently violate these assumptions. We review the literature on weak instruments in linear IV regression with an emphasis on results for nonhomoskedastic (heteroskedastic, serially correlated, or clustered) data. To assess the practical importance of weak instruments, we also report tabulations and simulations based on a survey of papers published in the American Economic Review from 2014 to 2018 that use IV. These results suggest that weak instruments remain an important issue for empirical practice, and that there are simple steps that researchers can take to better handle weak instruments in applications.  more » « less
Award ID(s):
1654234
PAR ID:
10142670
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Annual Review of Economics
Volume:
11
Issue:
1
ISSN:
1941-1383
Page Range / eLocation ID:
727 to 753
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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