Chemla, G and Hennessy, C (2019) Controls, belief updating, and bias in medical RCTs. Journal of Economic Theory, 184. ISSN 0022-0531
Abstract
We develop a formal model of placebo effects. If subjects in seemingly-ideal single-stage RCTs [Randomized Control Trials] update beliefs about breakthroughs based upon personal physiological responses, mental effects differ across medications received, treatment versus control. Consequently, the average cross-arm health difference becomes a biased estimator. Constructively, we show: bias can be altered through choice of control; higher-efficacy controls mitigate upward bias; and efficacy states can be revealed through controls of intermediate efficacy or controls that mimic a subset of efficacy states. Consistent with experimental evidence, our theory implies outcomes within-arm and cross-arm differences can be non-monotone in treatment probability. Finally, we develop novel differences-in-differences and triangle equality tests to detect RCT bias.
More Details
Item Type: | Article |
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Subject Areas: | Finance |
Funder Name: | European Research Council |
Date Deposited: | 20 Sep 2019 16:23 |
Date of first compliant deposit: | 07 Jan 2020 |
Last Modified: | 13 Dec 2024 03:11 |
URI: | https://lbsresearch.london.edu/id/eprint/1205 |