Behavioral Feedback: Do Individual Choices Influence Scientific Results?

43 Pages Posted: 5 Nov 2018

Date Written: November 2018


In many health domains, we are concerned that observed links - for example, between “healthy” behaviors and good outcomes - are driven by selection into behavior. This paper considers the additional factor that these selection patterns may vary over time. When a particular health behavior becomes more recommended, the take-up of the behavior may be larger among people with other positive health behaviors. Such changes in selection would make it even more difficult to learn about causal effects. I formalize this change in selection in a simple model. I test for evidence of these patterns in the context of diet and vitamin supplementation. Using both microdata and evidence from published results I show that selection varies over time with recommendations about behavior and that estimates of the relationship between health outcomes and health behaviors vary over time in the same way. I show that adjustment for selection on observables is insufficient to address the bias. I suggest a possible robustness approach relying on assumptions about proportional selection of observed and unobserved variables.

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Suggested Citation

Oster, Emily, Behavioral Feedback: Do Individual Choices Influence Scientific Results? (November 2018). NBER Working Paper No. w25225. Available at SSRN:

Emily Oster (Contact Author)

Brown University

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