contagion from purely observational data. It is especially helpful as a corrective to some of the more extreme statements of …

analyses of the type employed by Christakis and Fowler will still yield valid tests of the null of no social contagion, even … additional period, then under the null of no contagion, the problems of model inconsistency and statistical dependence … effectively disappear which allow for testing for contagion. Our results clarify the setting in which even "flawed" social network …