"Influence and Correlation in Social Networks" - Anagnostopoulos et al.

The authors describe a statistical test for actions in social networks.
This test helps to distinguish correlation from causality for information propagation in social networks.
Hereby, the author's test first calculates the probability for one user influencing the other user.
Afterwards, they shuffle action times of the user and test again.
To get a detailed insight into the statistical concept please take a look at the paper.