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Social contagion story update

June 8, 2011

July last year I wrote a note about the stream of papers by Nicholas Christakis and James Fowler (or CF) and coauthors on social contagion of many things (obesity, smoking, loneliness to name the few). I also wrote about a paper by Russel Lyons that provided a detailed critique of the analyzes presented in the papers by CF. See my earlier post for details.

Meanwhile, the paper by Lyons, which was available through ArXiv repository since July last year, got published in Statistics, Politics, and Policy journal here (thanks to Ilan Talmud for noticing that). All the substantial points remained largely unchanged as compared to the ArXiv paper. However, the author supplemented the paper with a truly hair-raising account of the struggle he had to go through to publish the paper: rejections from several journals without reviews or even reasonable explanations. I definitely recommend reading it.

Using the occasion, I also recommend two other papers related to this “debate”:

The first one is a response of Christakis & Fowler to some other critical comments on related issues:

Fowler, James H. and Nicholas A. Christakis. 2008b. “Estimating peer effects on health in social networks: A response to Cohen-Cole and Fletcher and Trogdon, Nonnemaker, and Pais.” Journal of Health Economics 27:1400–1405.

The second one is by Hans Noel and Brendan Nyhan

The “Unfriending” Problem The Consequences of Homophily in Friendship Retention for Causal Estimates of Social Influence” (download)

in which they use MCMC simulations to show, in short, how network homophily could have confounded the purported contagion effects reported in the studies by CF.

  1. June 9, 2011 17:38

    There’s also the recent paper by Chalizi and Thomas, who argue more generally that ALL observational network studies on contagion are problematic, i.e., “Homophily and Contagion Are Generically Confounded in Observational Social Network Studies.” They specifically take C&F as an example.

  2. June 9, 2011 17:40

    Forgot to include the link to the C&T paper:


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