  The chronic widespread misuse of statistics is usually inadvertent, not
intentional. We find cautionary examples in a series of recent papers by
Christakis and Fowler that advance statistical arguments for the transmission
via social networks of various personal characteristics, including obesity,
smoking cessation, happiness, and loneliness. Those papers also assert that
such influence extends to three degrees of separation in social networks. We
shall show that these conclusions do not follow from Christakis and Fowler's
statistical analyses. In fact, their studies even provide some evidence against
the existence of such transmission. The errors that we expose arose, in part,
because the assumptions behind the statistical procedures used were
insufficiently examined, not only by the authors, but also by the reviewers.
Our examples are instructive because the practitioners are highly reputed,
their results have received enormous popular attention, and the journals that
published their studies are among the most respected in the world. An
educational bonus emerges from the difficulty we report in getting our critique
published. We discuss the relevance of this episode to understanding
statistical literacy and the role of scientific review, as well as to reforming
statistics education.
