I had in mind cases where a book might surge from being checked out once a year to being checked out once a month, maybe something like a historical book about

I had in mind cases where a book might surge from being checked out once a year to being checked out once a month, maybe something like a historical book about a specific Native American tribe when they're in the news for a while, or something. It seems like one of those "big data things", looking for odd relationships between things, like vampires being more popular during Democratic presidencies and zombies being more popular during Republican ones (as a tongue-in-cheek example: http://www.mrscienceshow.com/2009/05/correlation-of-week-zombies-vampires.html http://www.mrscienceshow.com/2009/05/correlation-of-week-zom...) The librarian in the article cited a future need to re-buy a book that was previously culled. I guess what I'm trying to work toward would be an idea of finding non-obvious signs of when certain categories of books might become more and less popular, what patterns (if any) govern that schedule, and from that, make predictions of expected cost in keeping certain books around, as opposed to selling them off immediately. I'm playing around with the idea of whether there's a better way than "current readership + age of book" to predict, to a useful degree, the probability of it being more or less popular in the future.