Efficient estimation with many weak instruments using regularization techniques

Marine Carrasco and Guy Tchuente

Studies in Economics from School of Economics, University of Kent

Abstract: The problem of weak instruments is due to a very small concentration parameter. To boost the concentration parameter, we propose to increase the number of instruments to a large number or even up to a continuum. However, in finite samples, the inclusion of an excessive number of moments may be harmful. To address this issue, we use regularization techniques as in Carrasco (2012) and Carrasco and Tchuente (2013). We show that normalized regularized 2SLS and LIML are consistent and asymptotically normally distributed. Moreover, their asymptotic variances reach the semiparametric efficiency bound unlike most competing estimators. Our simulations show that the leading regularized estimators (LF and T of LIML) work very well (are nearly median unbiased) even in the case of relatively weak instruments. An application to the effect of institutions on output growth completes the paper.

Keywords: many weak instruments; LIML; 2SLS; regularization methods (search for similar items in EconPapers)
JEL-codes: C13 (search for similar items in EconPapers)
Date: 2015-07
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Citations: View citations in EconPapers (2)

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Related works:
Journal Article: Efficient Estimation with Many Weak Instruments Using Regularization Techniques (2016)
Working Paper: Efficient estimation with many weak instruments using regularization techniques (2013)
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Persistent link: https://EconPapers.repec.org/RePEc:ukc:ukcedp:1517

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