Is Obesity Contagious? Social Networks vs. Environmental Factors in the Obesity Epidemic
University of Maryland - College Park
Jason M. Fletcher
Yale University - School of Public Health; University of Wisconsin - Madison - Robert M. La Follette School of Public Affairs
FRB of Boston Quantitative Analysis Unit Working Paper No. QAU08-2
Journal of Health Economics, Forthcoming
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.
Number of Pages in PDF File: 13
Keywords: Obesity, Peer Effects, Social Networks
JEL Classification: D10, D71, I19, J11, Z13working papers series
Date posted: February 27, 2008
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