Semiparametric Estimation of Instrumental Variable Models for Causal Effects

Alberto Abadie ()

No 260, NBER Technical Working Papers from National Bureau of Economic Research, Inc

Abstract: This article introduces a new class of instrumental variable (IV) estimators of causal treatment effects for linear and nonlinear models with covariates. The rationale for focusing on nonlinear models is to improve the approximation to the causal response function of interest. For example, if the dependent variable is binary or limited, or if the effect of the treatment varies with covariates, a nonlinear model is likely to be appropriate. However, identification is not attained through functional form restrictions. This paper shows how to estimate a well-defined approximation to a nonlinear causal response function of unknown functional form using simple parametric models. As an important special case, I introduce a linear model that provides the best linear approximation to an underlying causal relation. It is shown that Two Stage Least Squares (2SLS) does not always have this property and some possible interpretations of 2SLS coefficients are brie y studied. The ideas and estimators in this paper are illustrated using instrumental variables to estimate the effects of 401(k) retirement programs on savings.

JEL-codes: C14 C21 (search for similar items in EconPapers)
Date: 2000-09
Note: TWP PE
View list of references View citations in EconPapers

Downloads: (external link)
http://www.nber.org/papers/t0260.pdf (application/pdf)
Access to the full text is generally limited to series subscribers, however if the top level domain of the client browser is in a developing country or transition economy free access is provided. More information about subscriptions and free access is available at http://www.nber.org/wwphelp.html.

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: http://EconPapers.repec.org/RePEc:nbr:nberte:0260

Ordering information: This working paper can be ordered from
http://www.nber.org/papers/t0260
The price is Paper copy available by mail.

Access Statistics for this paper

More papers in NBER Technical Working Papers from National Bureau of Economic Research, Inc
Address: National Bureau of Economic Research, 1050 Massachusetts Avenue Cambridge, MA 02138, U.S.A.
Contact information at EDIRC.
Series data maintained by ().