Figure 2.

A rule-based categorization of the tweets into promotional HPV-related information and consumers’ discussions. *If a tweet does not include a Uniform Resource Locator (URL), it is considered as a consumer discussion. Even if it is a retweet (ie, starts with “rt”), the retweet is consumers’ discussions, as we considered that the user who retweeted agrees with the original user’s discussion and the original tweet is also consumers’ discussions (as there is no URL). When a tweet contains URLs, the rules are more complex. First, if a tweet is quoting another tweet or web resource (ie, “is_quote_status” = True) and is not a retweet, it is considered as consumers’ discussions. In the special case in which the tweet is a retweet of a quoting tweet, we consider this as promotional information because we are unable to determine which of the comments the current user agrees with. In essence, when a tweet is a retweet, we classified the retweet based on the original tweet. Second, if a tweet is not a quoting tweet, it is considered as promotional information. HPV: human papillomavirus.