S-WoPEc
 
Scandinavian Working Papers in Economics
HomeAboutSeriesSubject/JEL codesAdvanced Search
IFAU - Institute for Evaluation of Labour Market and Education Policy Working Paper Series
IFAU - Institute for Evaluation of Labour Market and Education Policy

No 2012:14:
Testing for nonparametric identification of causal effects in the presence of a quasi-instrument

Xavier de Luna () and Per Johansson ()

Abstract: The identification of average causal effects of a treatment in observational studies is typically based either on the unconfoundedness assumption or on the availability of an instrument. When available, instruments may also be used to test for the unconfoundedness assumption (exogeneity of the treatment). In this paper, we define variables which we call quasi-instruments because they allow us to test for the unconfoundedness assumption although they do not necessarily yield nonparametric identification of the average causal effect. A quasi-instrument is defined as an instrument except for that its relation to the treatment is allowed to be confounded by unobservables, thereby resulting in a wider range of potential applications. We propose a test for the unconfoundedness assumption based on a quasi-instrument and give conditions under which the test has power. We perform a simulation study and apply the results to a case study where the interest lies in evaluating the effect of job practice on employment.

Keywords: Quasi-instrument; causal effects; (follow links to similar papers)

JEL-Codes: C14; (follow links to similar papers)

23 pages, June 25, 2012

Before downloading any of the electronic versions below you should read our statement on copyright.
Download GhostScript for viewing Postscript files and the Acrobat Reader for viewing and printing pdf files.

Full text versions of the paper:

wp12-14-Testing-for-nonpa ... of-a-quasi-instrument.pdf    PDF-file
Download Statistics
This paper is published as:
de Luna, Xavier and Per Johansson, (2014), 'Testing for the Unconfoundedness Assumption Using an Instrumental Assumption', Journal of Causal Inference, Vol. 2, April, No. 2, pages 187-199



Questions (including download problems) about the papers in this series should be directed to Monica Fńllgren ()
Report other problems with accessing this service to Sune Karlsson () or Helena Lundin ().

Programing by
Design by Joachim Ekebom

Handle: RePEc:hhs:ifauwp:2012_014 This page was generated on 2016-01-24 15:55:01