This question -- SVD for PCA: Why would one standardize the data matrix? -- was closed as a duplicate at 16:59:24 (nine minutes after having been posted). I can swear I saw it closed and without answers (that is when I wrote my comment). But then at 17:00:02 an answer was posted.

Answers cannot be posted to closed questions. So this is clearly due to some glitch or a loophole that allowed posting an answer within very short time after the question closure. I remember discussing a similar case in chat some time ago and one of the mods said that indeed it can happen.

I am curious what exactly the glitch/loophole is, and whether it is a bug or by design.

(Is it that if somebody opened the question page before the Q is closed and so can access the answer form, then they will be able to post an answer? So the SE software does not check if the Q is closed when receiving an A? Or it does check, but intentionally allows some leeway? Or is this leeway an unintentional consequence of some database updates taking time to propagate? Etc.)


1 Answer 1


There's a grace period after closure where an answer can still be accepted (however the Post Your Answer button becomes disabled, so you have to be clever enough to find a way around that).

In this case the posting of the answer came so close in time after closure that the button was probably still working at that moment.

  • $\begingroup$ Thanks, this answers it. I should have searched on Meta.SE... (Your link also mentions that the Post Your Answer button might never become disabled in a mobile app, so perhaps that is what Kodiologist was using.) $\endgroup$
    – amoeba
    Commented Sep 15, 2016 at 20:54
  • $\begingroup$ @amoeba I was using plain old Firefox on a Linux PC. I didn't notice the closure till after I submitted my answer, though. $\endgroup$ Commented Sep 15, 2016 at 21:36

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