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I know "Hot" questions are based on some sort of views/velocity criteria but does anyone know the actual algorithm used?


I was considering a feature suggestion about the "Hot" tab, but I don't have enough information to speak intelligently about it.

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What hot questions? There are two kinds and for all we know they may share the same hotness formula or have two different formulae. One is the "hot tab" of each site, the other is the "pan-SE hot questions tab" in the "StackExchange" popup in the top-left of every page (which doesn't seem to have a URL but rather is only accessible by JavaScript). –  hippietrail Dec 8 '11 at 16:06
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This question referred to the 'hot' tab on Stack Exchange sites. This question was asked 2-1/2 years ago in July '09, when there was no pan-SE functionality. And, no, I don't know if they use the same algorithm or not. –  Robert Cartaino Dec 8 '11 at 16:28

1 Answer 1

up vote 29 down vote accepted

What formula should be used to determine "hot" questions?

Based on my analysis of the above and the comments so far, here's the second version of what I have implemented so far. This might suck. I don't know:

(log(Qviews)*4) + ((Qanswers * Qscore)/5) + sum(Ascores)
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((QageInHours+1) - ((QageInHours - Qupdated)/2)) ^ 1.5

Note that I do not weight an accepted answer very heavily. This is intentional, as I feel accepted answers are a fine social contract, but not necessarily a good data point for question or answer quality.

Keep in mind that the formula used to determine the network hot list (including the one on the homepage sidebar) is somewhat different from this; see: How do the “arbitrary hotness points” work on the new Stack Exchange home page?

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Could you change the log to log10 (logarithm to the base 10) or the equivalent in the language you've implemented it in? That will decrease the weighting given to question views by a factor of ~2.3 Right now it's heavily skewed towards more views than quality (votes) –  Lorem Ipsum Aug 18 '11 at 16:42
    
Does this cover both the per-site hot list and the pan-SE hot list? the latter seems to take into account how young or small a site is, at least during beta. –  hippietrail Dec 8 '11 at 16:08
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I don't quite follow the quoitient. Doesn't that penalise recently updated questions? Or is that the point? –  Pureferret Jan 18 '12 at 18:36
    
How would all of that criteria, ie views, score, updated, differ from the activity sort? How is sorting on activity different from sorting on hot... Is a "hot" question one that simply has a lot of activity over a short amount of time? –  user159540 Feb 14 at 0:15

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