For a very long time, my impact has approached the total number of users. Now it is 14K, while the total user number is about 13K! What algorithm is behind this?

Obviously, many people read our posts without registering. Are these counted? Are they uniformly divided among us?

  • You wrote more than one post …
    – chirlu
    Commented Jul 18, 2016 at 8:31

1 Answer 1


The "people reached" impact factor is a rough estimate of how many people had read any of your posts while browsing the Stack Exchange Network. It is based on views, so a single user can count multiple times if they viewed several posts of yours. Views of unregistered visitors add to this as well.

There is an algorithm involved to find the likeliness of any of your posts was actually read. The more elaborate reasoning on this can be found in this related post:

  • I am surprised they don't use a matrix tracking, whether users have upvoted each other. It would be initially sparse and possibly over time could be truncated to new users. For our case 10Kx10K there should be no memory issue. It need not be updated live!
    – Ludi
    Commented Jul 18, 2016 at 11:16
  • @Ludi: Both in your question and this comment, I have the impression that you are starting from a wrong idea what this feature is about.
    – chirlu
    Commented Jul 18, 2016 at 14:10
  • @chirlu I was indeed, on the other hand, having read the post on meta now, it seems to me that most people originally desired exactly what I assumed it was: an indicator of the number of people reached
    – Ludi
    Commented Jul 18, 2016 at 17:30

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