TABLE 2. Description of Extracted Features.

Tweet-level features
	No. of retweets
	No. of favorites
	Whether the tweet includes a question mark
	Whether the tweet is a duplicate of its source
	Whether the tweet contains a URL
	No. of URLs embedded in the tweet
	No. of mentions
	No. of hashtags
	No. of words in the tweet except the source author’s screen name
User-level features
	No. of tweets user has posted
	No. of public lists user belongs to
	No. of followers
	No. of followings
	Whether the user profile has a background image
	User’s reputation (i.e., followers/(followings+1))
	No. of tweets user has liked so far
	Account age in days
	Whether the profile is verified
	User engagement (i.e., # posts / (account age+1))
	Following rate (i.e., followings / (account age+1))
	Favorite rate (i.e., user favorites / (account age+1))
	Whether geolocation is enabled
	Whether the user has a description
	No. of words in the user’s description
	No. of characters in the user’s name including white space
	Whether the user is the source tweet’s author