Combining Two Consistent Estimators

This chapter shows how a weighted average of a forward and reverse Jackknife IV estimator (JIVE) yields estimators that are robust against heteroscedasticity and many instruments. These estimators, called HFUL (Heteroscedasticity robust Fuller) and HLIM (Heteroskedasticity robust limited information...

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Bibliographic Details
Main Authors: Chao, John C., Hausman, Jerry A., Newey, Whitney K., Swanson, Norman R., Woutersen, Tiemen
Other Authors: Massachusetts Institute of Technology. Department of Economics
Format: Article
Language:en_US
Published: Emerald (MCB UP) 2013
Online Access:http://hdl.handle.net/1721.1/82655
https://orcid.org/0000-0003-2699-4704
https://orcid.org/0000-0002-5433-9435
Description
Summary:This chapter shows how a weighted average of a forward and reverse Jackknife IV estimator (JIVE) yields estimators that are robust against heteroscedasticity and many instruments. These estimators, called HFUL (Heteroscedasticity robust Fuller) and HLIM (Heteroskedasticity robust limited information maximum likelihood (LIML)) were introduced by Hausman, Newey, Woutersen, Chao, and Swanson (2012), but without derivation. Combining consistent estimators is a theme that is associated with Jerry Hausman and, therefore, we present this derivation in this volume. Additionally, and in order to further understand and interpret HFUL and HLIM in the context of jackknife type variance ratio estimators, we show that a new variant of HLIM, under specific grouped data settings with dummy instruments, simplifies to the Bekker and van der Ploeg (2005) MM (method of moments) estimator.