Ask HN: Why do so many "Ask HN:" posts seem to cluster together?

[OzzyOsbourne]

I have noticed that quite often. Ask HN posts seem to clump together. Does anyone know if this is:

a. pure coincidence b. how HN ranks posts c. Some statistical correlation that exists between ask HN posts, that binds them more tightly than other posts. I would think it has to do with ask HN posts' objective: to be answered. d. total fluke just my experience

[OzzyOsbourne]

http://imagepaste.nullnetwork.net/viewimage.php?id=2494 - a screenshot

[ig1]

There's a special penalty that gets applied to Ask HN posts, I guess that's what's responsible for any clustering.

[glimcat]

My first guess would be triggering (Person B sees a post by Person A and decides to post their own).