TY  - JOUR
AU  - Heckman, James J
AU  - Urzua, Sergio
TI  - Comparing IV With Structural Models: What Simple IV Can and Cannot Identify
JF  - National Bureau of Economic Research Working Paper Series
VL  - No. 14706
PY  - 2009
Y2  - February 2009
DO  - 10.3386/w14706
UR  - http://www.nber.org/papers/w14706
L1  - http://www.nber.org/papers/w14706.pdf
N1  - Author contact info:
James J. Heckman
Center for the Economics of
Human Development
University of Chicago
1126 East 59th Street
Chicago, IL 60637
Tel: 773/702-0634
Fax: 773/702-8490
E-Mail: jjh@uchicago.edu

Sergio S. Urzúa
Department of Economics
University of Maryland
3115J Tydings Hall
College Park, MD 20742
Tel: 301-405-3266
E-Mail: urzua@econ.umd.edu
AB  - This paper compares the economic questions addressed by instrumental variables estimators with those addressed by structural approaches. We discuss Marschak's Maxim: estimators should be selected on the basis of their ability to answer well-posed economic problems with minimal assumptions. A key identifying assumption that allows structural methods to be more informative than IV can be tested with data and does not have to be imposed.
ER  -