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Is Obesity Contagious? Social Networks vs. Environmental Factors in the Obesity Epidemic

13 Pages Posted: 27 Feb 2008  

Ethan Cohen-Cole

Econ One Research

Jason M. Fletcher

University of Wisconsin - Madison - Robert M. La Follette School of Public Affairs; Yale University - School of Public Health

Date Written: April 2008

Abstract

This note's aim is to investigate the sensitivity of Christakis and Fowler's claim (NEJM July 26, 2007) that obesity has spread through social networks. It is well known in the economics literature that failure to include contextual effects can lead to spurious inference on social network effects. We replicate the NEJM results using their specification and a complementary dataset. We find that point estimates of the social network effect are reduced and become statistically indistinguishable from zero once standard econometric techniques are implemented. We further note the presence of estimation bias resulting from use of an incorrectly specified dynamic model.

Keywords: Obesity, Peer Effects, Social Networks

JEL Classification: D10, D71, I19, J11, Z13

Suggested Citation

Cohen-Cole, Ethan and Fletcher, Jason M., Is Obesity Contagious? Social Networks vs. Environmental Factors in the Obesity Epidemic (April 2008). FRB of Boston Quantitative Analysis Unit Working Paper No. QAU08-2; Journal of Health Economics, Forthcoming. Available at SSRN: https://ssrn.com/abstract=1098321 or http://dx.doi.org/10.2139/ssrn.1098321

Ethan Cohen-Cole (Contact Author)

Econ One Research ( email )

United States

Jason M. Fletcher

University of Wisconsin - Madison - Robert M. La Follette School of Public Affairs ( email )

1180 Observatory Drive
Madison, WI 53706-1393
United States

Yale University - School of Public Health ( email )

PO Box 208034
60 College Street
New Haven, CT 06520-8034
United States

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