R2-D2_hates_lemon's blog

By R2-D2_hates_lemon, history, 2 months ago, In English,

Hi everyone! In recent contests, my friends and I did not perform well. However, our ratings still increased somehow. In addition, CF predictor is no longer precise these days. Maybe I'm not the only one who feel strange. Then, did Codeforces change their formula for rating system?

 
 
 
 
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2 months ago, # |
Rev. 2   Vote: I like it +12 Vote: I do not like it

I only solved Div2 [A — B] and my rating increased to 1653! I thought I was going back to Specialist LOL

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2 months ago, # |
  Vote: I like it +19 Vote: I do not like it

maybe it's because the number of participants has increased significantly due to lockdown

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    2 months ago, # ^ |
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    The formula is stationary, right? So the number of participants should effect nothing.

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      2 months ago, # ^ |
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      The predictions were good enough, in today's contest atleast

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        2 months ago, # ^ |
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        Well, -8 became +5 and +43 became +92. I dont think the predictions were good!

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          2 months ago, # ^ |
            Vote: I like it -11 Vote: I do not like it

          How so? There's a huge difference when you get rank 500 with 1000 people vs 10000 people. Number of participants is probably there in their formula.

          Also most of the newcomers are beginners so they basically just increase the number of participants and since rating change is inversely proportional to participants you get a higher rating than expected

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            2 months ago, # ^ |
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            I understand what u said. My question is that CF predictor is also built based on CF formula in which it already considered your situation when the number of participants is large.

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          2 months ago, # ^ |
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          +82 became +86....i think it's good enough

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      2 months ago, # ^ |
      Rev. 2   Vote: I like it +17 Vote: I do not like it

      dude, do you know how does the formula work? it uses your expected place which is counted according to your rating and ratings of all other participants.

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2 months ago, # |
  Vote: I like it +35 Vote: I do not like it

CF Predictor has never been more than several points off for me personally. It's easy to trick yourself into thinking that you didn't do as well as you did, given the large number of participants in the past few rounds. Your rating change doesn't take into account your absolute rank, but rather how you perform relative to the rest of the pool of participants.

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2 months ago, # |
Rev. 2   Vote: I like it +7 Vote: I do not like it

Probably because so many users participate in rounds nowadays, when more users with higher rating than you gets below you in standings your rating will increase more.

About the predictor It was 100% precise with me, maybe you didn't reload the page and standings have changed after you took a look at the predictor???

Edit: I just compared the rating change, you are right the predictor have some mistakes in Div. 2

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2 months ago, # |
Rev. 2   Vote: I like it +59 Vote: I do not like it

I believe today was the first when more than 10k contestants took part in a rated round. As I remember, I didn't considered such option when I was developing CF-Predictor.

This should be quite easy fix, I'll work on it on weekends.

P.S. As you can see prediction for the div. 1 is accurate, so formula hasn't changed.

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2 months ago, # |
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It mainly happened because div2 C was solved by quite less number of participants. It is rated 1800 as you can see...So if a 1600 rated participant is not able to solve the 3rd problem and he solves the first two quickly, then his rating will definitely increase

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2 months ago, # |
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I think because the number of participants during the quarantine time is high. So the more the under-rating-participants there are in the contest, the more rating you will increase after the contest

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2 months ago, # |
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You are the only one who feels strange. It's not changed.

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2 months ago, # |
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And I thought it is the power of FAN CLUB!!!

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2 months ago, # |
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I think maybe it's base on your rank ratio. Ex: your rank is 1000 and we have 10000 participants so you have rank ratio 0.1, it's same as you archive rank 100 and only 1000 participants in the contest.