Nancy Cartwright

Department of Philosophy
Durham University
50 Old Elvet
Durham, UK DH1 3HN

E-Mail: EmailAddress: hidden: you can email any NBER-related person as first underscore last at nber dot org
Institutional Affiliations: Durham University and University of California, San Diego

NBER Working Papers and Publications

September 2016Understanding and Misunderstanding Randomized Controlled Trials
with Angus Deaton: w22595
RCTs would be more useful if there were more realistic expectations of them and if their pitfalls were better recognized. For example, and contrary to many claims in the applied literature, randomization does not equalize everything but the treatment across treatments and controls, it does not automatically deliver a precise estimate of the average treatment effect (ATE), and it does not relieve us of the need to think about (observed or unobserved) confounders. Estimates apply to the trial sample only, sometimes a convenience sample, and usually selected; justification is required to extend them to other groups, including any population to which the trial sample belongs. Demanding “external validity” is unhelpful because it expects too much of an RCT while undervaluing its contribution. S...

Published: Angus Deaton & Nancy Cartwright, 2017. "Understanding and misunderstanding randomized controlled trials," Social Science & Medicine, . citation courtesy of

National Bureau of Economic Research
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