Radin_Zahedi's blog

Bug when ratings are rolled back
By Radin_Zahedi, history, 4 years ago, In English

I believe there's a bug in CodeForces ratings, because when ratings are rolled back, my previous contest rating is increased by 2, and it's now the second time it happens. What is the cause?

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  • +11
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4 years ago, # |
  Vote: I like it +40 Vote: I do not like it

Maybe cheaters were disqualified and your ratings increased.

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4 years ago, # |
  Vote: I like it +17 Vote: I do not like it

I guess the ratings are rolled back when some solutions get plag and contest get skipped for some participants and if they were better in rating than you then your rating improves .So, when they are awarded back delta might increase.

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4 years ago, # |
  Vote: I like it +45 Vote: I do not like it

That's the whole point of rolling back ratings

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4 years ago, # |
← Rev. 2   Vote: I like it +11 Vote: I do not like it

I remember Mike writing somewhere that ratings are rolled back when he is removing people for cheating. Ratings were prematurely updated so that people can participate in the upcoming contests otherwise people who became CM from expert in the last Div 2 will lose rating after participating in an educational round. So to prevent from this, ratings are updated and then later rolled back to remove cheaters.

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4 years ago, # |
  Vote: I like it +5 Vote: I do not like it

Hello dear Radin !

Roll back of the ratings is for identifying the cheaters, and after identifying the cheaters, they will be removed from the competition and your rank will improve and you will get more ratings. I hope it was useful!

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4 years ago, # |
← Rev. 4   Vote: I like it +3 Vote: I do not like it

The cheaters were moved and then your ratings increased :)
btw, the rating of one of my friend Pub decreased by 1 when ratings are rolled back. I just want to ask for the reason because he says that he didn't do something wrong before rolling back.

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    4 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I'm here qaq

    I checked it again, and I'm sure that my score is still 2360 now, but my rating decreased:(

    +550 -> +549

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    6 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    It probably decreases when more no. of cheaters got disqualified who initially had higher rank than you than the no. of cheaters who had lower rank..

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5 months ago, # |
  Vote: I like it +1 Vote: I do not like it

In my case, my rating was initially increased to 1209 but after the rating changes it went down to 1191 (a +23 increase in place of the +41 given earlier), any reason for this?

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