Open Access. Powered by Scholars. Published by Universities.®
Social and Behavioral Sciences Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 2 of 2
Full-Text Articles in Social and Behavioral Sciences
Inference With Weak Instruments, Donald W.K. Andrews, James H. Stock
Inference With Weak Instruments, Donald W.K. Andrews, James H. Stock
Cowles Foundation Discussion Papers
This paper reviews recent developments in methods for dealing with weak instruments (IVs) in IV regression models. The focus is more on tests (and confidence intervals derived from tests) than estimators. The paper also presents new testing results under “many weak IV asymptotics,” which are relevant when the number of IVs is large and the coefficients on the IVs are relatively small. Asymptotic power envelopes for invariant tests are established. Power comparisons of the conditional likelihood ratio (CLR), Anderson-Rubin, and Lagrange multiplier tests are made. Numerical results show that the CLR test is on the asymptotic power envelope. This holds …
Exactly Distribution-Free Inference In Instrumental Variables Regression With Possibly Weak Instruments, Donald W.K. Andrews, Vadim Marmer
Exactly Distribution-Free Inference In Instrumental Variables Regression With Possibly Weak Instruments, Donald W.K. Andrews, Vadim Marmer
Cowles Foundation Discussion Papers
This paper introduces a rank-based test for the instrumental variables regression model that dominates the Anderson-Rubin test in terms of finite sample size and asymptotic power in certain circumstances. The test has correct size for any distribution of the errors with weak or strong instruments. The test has noticeably higher power than the Anderson-Rubin test when the error distribution has thick tails and comparable power otherwise. Like the Anderson-Rubin test, the rank tests considered here perform best, relative to other available tests, in exactly-identified models.