TY  - JOUR
AU  - Imbens,Guido W.
TI  - The Role of the Propensity Score in Estimating Dose-Response Functions
JF  - National Bureau of Economic Research Technical Working Paper Series
VL  - No. 237
PY  - 1999
Y2  - April 1999
UR  - http://www.nber.org/papers/t0237
L1  - http://www.nber.org/papers/t0237.pdf
N1  - Author contact info:
Guido Imbens
Graduate School of Business
Stanford University
655 Knight Way
Stanford, CA 94305
Tel: 617/384-7485
Fax: 617/495-7730
E-Mail: Imbens@stanford.edu
AB  - Estimation of average treatment effects in observational, or non-experimental in pre-treatment variables. If the number of pre-treatment variables is large, and their distribution varies substantially with treatment status, standard adjustment methods such as covariance adjustment are often inadequate. Rosenbaum and Rubin (1983) propose an alternative method for adjusting for pre-treatment variables based on the propensity score conditional probability of receiving the treatment given pre-treatment variables. They demonstrate that adjusting solely for the propensity score removes all the bias associated with differences in pre-treatment variables between treatment and control groups. The Rosenbaum-Rubin proposals deal exclusively with the case where treatment takes on only two values. In this paper an extension of this methodology is proposed that allows for estimation of average causal effects with multi-valued treatments while maintaining the advantages of the propensity score approach.
ER  -