Are there guidelines on direction for merging questions (which question to close/merge?)

Question

Given two duplicate questions, are there any guidelines on how moderators determine which question is closed/merged, and which question will remain open, or is it up to the moderator to decide on a case-by-case basis?

I've seen a number of merged questions, where sometimes the earlier of the two questions is kept, while sometimes it's the better worded question; when a question is migrated and the OP doesn't have an account on the new site, it might be merged to the question that has an account (or is more active).

I'm not criticizing any of these decisions. I'm just curious if there is any policy (written or otherwise) on how moderators should decide the direction-to-merge. (And if so, what it is.)

Answer 1

First, in order to be considered a duplicate, the two questions must be nearly identical to each other. Questions that are merely similar are not necessarily duplicates. In particular, questions are not duplicates if the original question merely has an answer that satisfies the OP's question.

Consequently, there are reasons why questions don't get merged. Sometimes, the original is a canonical question with good answers; merging would simply litter the original question with unnecessary new answers. Sometimes questions get closed as dupes, but they're not close enough to the original for a merging to make sense.

That said, I generally pick the question with the better wording as the target for a merge. There's no written policy on this, that I know of.