Please use this identifier to cite or link to this item: http://hdl.handle.net/10419/130000
Authors: 
Carrasco, Marine
Tchuente, Guy
Year of Publication: 
2015
Series/Report no.: 
School of Economics Discussion Papers 1517
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.
Subjects: 
many weak instruments
LIML
2SLS
regularization methods
JEL: 
C13
Document Type: 
Working Paper

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