As a rough approximation, we check whether the changes in t 2 with respect to t 1 (which share the same topic and author) involve words or parts-of-speech that are associated with high retweet rate in a very large separate sample of unpaired tweets (retweets and replies discarded).
for each word w that appears more than 10 times, we compute the probability that tweets containing w are retweeted more than once, denoted by rspwq.