Title: Do Learning Communities Increase First Year College Retention? Testing Sample Selection and External Validity of Randomized Control Trials
Abstract: Voluntary selection into experimental samples is ubiquitous and may lead researchers to question the external validity of experimental findings. We introduce tests for sample selection on unobserved variables to discern the generalizability of randomized control trials. We estimate the impact of a learning community on first-year college retention using an RCT, and employ our tests in this setting. Intent-to-treat and local-average-treatment-effect estimates reveal no discernable programmatic effects. Our tests reveal that the experimental sample is positively selected on unobserved characteristics suggesting limited external validity. Finally, we compare observational and experimental estimates, considering the internal and external validity of both approaches to reflect on within-study comparisons themselves.
Publication Year: 2019
Publication Date: 2019-01-01
Language: en
Type: preprint
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