Powered by OpenAIRE graph
Found an issue? Give us feedback
addClaim

A Pretest and Higher Order Expansions in GMM for Nearly Weak Instruments

Authors: Mehmet Caner;

A Pretest and Higher Order Expansions in GMM for Nearly Weak Instruments

Abstract

In this paper we analyze GMM with strong and nearly-weak instruments. In the nearly weak-GMM, the correlation between the instruments and the first order conditions decline at a slower rate than root T. We find an important difference between the nearly-weak case and the weak case. Inference with point estimates is possible with Wald, Likelihood Ratio and Lagrange Multiplier tests in GMM with semi-weak instruments. The limit is the standard X squared limit. This is important from an applied perspective since tests on the weak case do depend on the true value and can only test simple null. Even though we may have all nearly-weak instruments in GMM it is still possible to test various hypothesis of interest. We also find a difference between nearly-weak and standard GMM cases. We derive higher order expansions for test statistics in the nearly-weak case, and we show that with declining quality of instruments finite sample behavior of these tests get worse, so standard GMM finite sample behavior is always better than nearly-weak GMM. Unlike the standard GMM, in the nearly-weak GMM we can not eliminate the second order terms from these test statistic's expansions. Wald test in Continuous Updating Estimator (CUE) have desirable properties in higher order expansions in the nearly-weak case. We also propose a pretest, bootstrap Kolmogorov-Smirnov test, to differentiate between weak and nearly-weak asymptotics. This is based on bootstrapping Wald CUE test. Since Wald CUE test has different limits under weak and nearly-weak cases and has good properties in the higher order expansions its empirical distribution can be used in a pretest. We also conduct some simulations and show that some of the asset pricing models conform to nearly-weak asymptotics. Clearly, this paper shows that when we move away from the standard GMM towards nearly-weak case, finite sample behavior suffers but large sample theory remains intact. But if we further move away from the nearly-weak case to weakly identified GMM the large sample theory changes too.

  • BIP!
    Impact byBIP!
    selected citations
    These citations are derived from selected sources.
    This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
    2
    popularity
    This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
    Average
    influence
    This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
    Average
    impulse
    This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
    Average
Powered by OpenAIRE graph
Found an issue? Give us feedback
selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
2
Average
Average
Average
Upload OA version
Are you the author of this publication? Upload your Open Access version to Zenodo!
It’s fast and easy, just two clicks!