External Treatment Effects and Program Implementation Bias

24 Pages Posted: 9 Mar 2000 Last revised: 9 Sep 2010

See all articles by Tomas Philipson

Tomas Philipson

University of Chicago; National Bureau of Economic Research (NBER)

Date Written: January 2000


This paper discusses the definition and identification of external treatment effects and experimental designs capable of detecting these effects. External effects occur when the outcome of a given individual is affected by the treatment assignments of other individuals. The paper argues that two-stage randomization schemes, which randomize allocation of treatments across communities and randomizes the treatments themselves within communities, are useful for identifying private and external treatment effects. The importance of external treatment effects are illustrated in the context of several health economics applications: the impact of R&D subsidies, smoking prevention programs for youth, and the evaluation of HIV-prevention programs currently taking place in Africa.

Suggested Citation

Philipson, Tomas J., External Treatment Effects and Program Implementation Bias (January 2000). NBER Working Paper No. t0250. Available at SSRN: https://ssrn.com/abstract=214653

Tomas J. Philipson (Contact Author)

University of Chicago ( email )

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