Working Paper: NBER ID: w18662
Authors: Joshua Angrist; Miikka Rokkanen
Abstract: In the canonical regression discontinuity (RD) design for applicants who face an award or admissions cutoff, causal effects are nonparametrically identified for those near the cutoff. The impact of treatment on inframarginal applicants is also of interest, but identification of such effects requires stronger assumptions than are required for identification at the cutoff. This paper discusses RD identification away from the cutoff. Our identification strategy exploits the availability of dependent variable predictors other than the running variable. Conditional on these predictors, the running variable is assumed to be ignorable. This identification strategy is illustrated with data on applicants to Boston exam schools. Functional-form-based extrapolation generates unsatisfying results in this context, either noisy or not very robust. By contrast, identification based on RD-specific conditional independence assumptions produces reasonably precise and surprisingly robust estimates of the effects of exam school attendance on inframarginal applicants. These estimates suggest that the causal effects of exam school attendance for 9th grade applicants with running variable values well away from admissions cutoffs differ little from those for applicants with values that put them on the margin of acceptance. An extension to fuzzy designs is shown to identify causal effects for compliers away from the cutoff.
Keywords: Regression Discontinuity; Educational Outcomes; Causal Inference
JEL Codes: C26; C31; C36; I21; I24; I28; J24
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| exam school attendance (I21) | achievement for marginal applicants at BLS (I24) |
| attendance at Obryant School of Math and Science (I24) | outcomes in English Language Arts (ELA) for marginal applicants (I24) |
| exam school attendance (I21) | achievement for applicants well above BLS cutoff (J68) |
| conditional independence assumption (C34) | identification of causal effects away from the cutoff (C24) |