Remember that paper that reported contagion of obesity? How’s it being cited nowadays?

I happened to be talking with some students today about social network research—we’re doing some followup on our penumbra paper—and the topic came up of the controversial study by Nicholas Christakis and James Fowler from the 2000s on the contagion of obesity.

We covered the topic in this space back in 2010 and 2011:

Controversy over social contagion

Controversy over the Christakis-Fowler findings on the contagion of obesity

Christakis-Fowler update

There we discussed the work of Christakis and Fowler; criticisms of that work by economists Jason Fletcher and Ethan Cohen-Cole, mathematician Russ Lyons, political scientists Hans Noel and Brendan Nyhan, and statisticians Cosma Shalizi and Andrew Thomas; and a response by the original authors, who wrote:

We do not claim that this work is the final word, but we do believe that it provides some novel, informative, and stimulating evidence regarding social contagion in longitudinally followed networks. Along with other scholars, we are working to develop new methods for identifying causal effects using social network data, and we believe that this area is ripe for statistical development as current methods have known and often unavoidable limitations.

The quick summary is:

1. Christakis and Fowler were doing interesting, innovative social science; they just went too far in the interpretation of their data. You know that saying, “high-risk, high-reward”? That’s what was happening here. There was potential high reward, but this study was ultimately a failure, except to the extent that failures can be useful too in helping us avoid certain dead-end paths in the future.

2. The claim of social contagion of obesity wasn’t supported by the data from the Framingham Health Study; the critics (Fletcher, Cohen-Cole, Lyons, Noel, Nyhan, Shalizi, and Thomas) were right.

3. There are social effects on attitudes and behavior, and they’re hard to study. As Christakis and Fowler wrote, this area is ripe for statistical development and also ripe for development in experimental design and data collection.

I was curious how this work is being cited, over 15 years later. Google Scholar lists 7000 citations. I searched for citations from this year, and here are the first few:

The first link above is to a book, and here’s the relevant passage:

The next is from a review article, which mentions the Christakis-Fowler paper as reference 31 here:

The next is a review on peer effects in “weight-related behaviours of young people,” which has this wrong summary:

Kinda makes me concerned about the rest of that literature review!

The next is a paper on “Community influence on microfinance loan defaults under crisis conditions,” which cites Christakis and Fowler not for their substantive claims but for a method they used:

It’s reference 40 in this next paper:

And it’s cited just a little bit too credulously as reference 15 here:

And then there’s this one:

They cited work of Brian “Pizzagate” Wansink! That’s not good. If this blog were a drinking game, everyone would have to take a swig right now.

Summary

The incorrect claim about contagion of obesity is out there, and just about nobody seems to be qualifying it with references to the critics. Sorry, Fletcher, Cohen-Cole, Lyons, Noel, Nyhan, Shalizi, and Thomas. Your hard work has come to (almost) naught.