I need to predict the number of retweeets a tweet receives as a function of (1) whether there is a hyperlink within the tweet's text and (2) the position of the hyperlink within the tweet. If a tweet doesn't contain a hyperlink then the position of the hyperlink within the tweet is a null value. Example data for this situation would be:
numberOfRetweets hyperlinkInTweet? positionOfHyperlink (dependent var) (binary, 0=no, 1=yes) (integer, 1 to 135) 5 0 null 10 1 50 35 1 12 0 0 null 0 1 5 : : :
If a tweet doesn't contain a hyperlink (hyperlinkInTweet = 0) then it cannot have a position within the tweet text where the hyperlink begins (positions range from 1 to 135 inclusive). I've toyed with the idea of using zero in place of null, but I have reservations about doing this. Exploratory analysis of the data indicates that about half of the tweets contain a hyperlink.
I'm wondering if this is a nested regression problem, but would be grateful for a second opinion on the best course of action for this problem. Many thanks.