Similar threads?

[El Chuxter]

This is just a question posed out of sheer curiosity, not a complaint or even a suggestion: How exactly does the forums system determine which threads show up at the bottom of the screen as "Similar Threads"? Is this a keyword thing, or is there someone who's paid full-time to determine this?

Some threads show no similar threads. And some have outlandish, supposedly similar threads.

[JediTricks]

I have been wondering that myself, and this very thread confirmed one of my theories, it seems to be based purely on thread title, every "Similar Thread" for this one has the word "threads" in its title, including a couple that only us moderators can see (I just tested to be sure :p).