A happy/unhappy new pair of studies

Investigator Stephen Black writes:

Much excitement in the news about a study just published in BMJ (British Medical Journal):

Dynamic spread of happiness in a large social network: longitudinal analysis over 20 years in the Framingham Heart Study,” James H Fowler and Nicholas A Christakis, BMJ 2008 337: a2338. The conclusion: “Peoples happiness depends on the happiness of others with whom they are connected.”

Which, of course, is a causal conclusion.

But lesser attention appears to have been paid to another study published simultaneously in the same issue: “Detecting implausible social network effects in acne, height, and headaches: longitudinal analysis,” Ethan Cohen-Cole and Jason M Fletcher, BMJ 2008;337:a2533

They found that a friend´s acne problems increased one’s own acne problems, a friend’s headaches increased one’s own headaches, and a friend’s height increased one’s own height. Given the first two, it seems one is better off without friends.

Their conclusion: “Researchers should be cautious in attributing correlations in health outcomes of close friends to social network effects, especially when environmental confounders are not adequately controlled for in the analysis”

Now see the first study again.

The same issue of BMJ also contains an editorial that gives further insight into this strange juxtaposition of a study and a study mocking it.