<p>This question -- <a href="https://stats.stackexchange.com/questions/235177">SVD for PCA: Why would one standardize the data matrix?</a> -- 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.</p>

<p>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.</p>

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

<p>(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.)</p>
