Regression discontinuity designs: A guide to practice

In regression discontinuity (RD) designs for evaluating causal effects of interventions, assignment to a treatment is
determined at least partly by the value of an observed covariate lying on either side of a fixed threshold. These designs were
first introduced in the evaluation literature by Thistlewaite and Campbell [1960. Regression-discontinuity analysis: an
alternative to the ex-post Facto experiment. Journal of Educational Psychology 51, 309–317] With the exception of a few
unpublished theoretical papers, these methods did not attract much attention in the economics literature until recently.
Starting in the late 1990s, there has been a large number of studies in economics applying and extending RD methods. In
this paper we review some of the practical and theoretical issues in implementation of RD methods.