title: A randomized experiment comparing random and cutoff-based assignment.
abstract: In this article, we review past studies comparing randomized experiments to regression discontinuity designs, mostly finding similar results, but with significant exceptions. The latter might be due to potential confounds of study characteristics with assignment method or with failure to estimate the same parameter over methods. In this study, we correct the problems by randomly assigning 588 participants to be in a randomized experiment or a regression discontinuity design in which they are otherwise treated identically, comparing results estimating both the same and different parameters. Analysis includes parametric, semiparametric, and nonparametric methods of modeling nonlinearities. Results suggest that estimates from regression discontinuity designs approximate the results of randomized experiments reasonably well but also raise the issue of what constitutes agreement between the 2 estimates.
authors.affiliation: School of Social Sciences, Humanities, and Arts, University of California, Merced, 5200 North Lake Road, Merced, CA 95343, USA. wshadish@ucmerced.edu
authors.forename: William R
authors.initials: WR
authors.lastname: Shadish
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Galindo
authors.forename: Vivian C
authors.initials: VC
authors.lastname: Wong
authors.forename: Peter M
authors.initials: PM
authors.lastname: Steiner
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Cook
mesh_terms: D000293:Adolescent; D015982:Bias; D003196:Computer Graphics; D003194:Computer-Assisted Instruction; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D020407:Internet; D008297:Male; D008433:Mathematics / Q000193:education*; D015233:Models, Statistical; D012107:Research Design / Q000706:statistics & numerical data; D018401:Sample Size; D014825:Vocabulary; D055815:Young Adult