A simple diagnostic to investigate instrument validity and heterogeneous effects when using a single instrument

Steven Dieterle and Andy Snell

Labour Economics, 2016, vol. 42, issue C, 76-86

Abstract: Many studies that use instrumental variables are based on a first stage linear in the instrument. Using only linear first stages may miss important information about effect heterogeneity and instrument validity. Analyzing fifteen studies using linear first stages, we find ten with significant nonlinearities. Six of these ten have statistically different second stage estimates. Additional analysis is necessary when results are sensitive to first stage choice. We provide a framework to reconcile these differences by determining those patterns of heterogeneity that are consistent with instrument validity. If these patterns violate economic reasoning, then the validity of the instrument is questioned.

Keywords: Instrumental variables; Heterogeneous treatment effects; Robustness check (search for similar items in EconPapers)
JEL-codes: C26 (search for similar items in EconPapers)
Date: 2016
References: Add references at CitEc
Citations: View citations in EconPapers (25)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0927537116300847
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:labeco:v:42:y:2016:i:c:p:76-86

DOI: 10.1016/j.labeco.2016.08.002

Access Statistics for this article

Labour Economics is currently edited by A. Ichino

More articles in Labour Economics from Elsevier
Bibliographic data for series maintained by Catherine Liu ().