Answers.Body: <p><strong>Neither</strong></p>
  <p>Elo-ratings are not ajusted for calculation after each game, they are not adjusted after each tournament either. They are adjusted <strong>each month</strong>.</p>
  <p>For all games played during one month, each player is supposed to have his last published elo-rating. If I am 2300 on the 1st of November and we play together November the 29th, your rating will be calculated by considering that you have faced a 2300-player. Whether I have gained 50 points in a previous tournament from 5 to 12 of November, or lost 100 points from novermber 16 to 23, will only be relevant for my rating on December 1st, and for my opponents in December and thereafter.</p>
  <p>In your example, the second method applies. But there won't be any ajustment after the tournament if one of your three players plays another tournament within the same month.</p>
  
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Answers.Text: So for every match that month, your expected score will be calculated assuming you are rated 2300 throughout the month. The grand total of all changes plus your old rating adds up to your new rating next month. Right? A bit like method 2, but over a whole month?
Answers.UserDisplayName: Myungjin Hyun
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Answers.Text: Absolutely. Also for calculating norms, btw.
Answers.UserDisplayName: Evargalo
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Answers.Text: Um, I'm not well-versed with such terms...a norm is something to do with IM and GM titles, right?
Answers.UserDisplayName: Myungjin Hyun
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Answers.Text: @HarryWeasley : yes, that's a step into becoming WIM / WGM / IM / IGM
Answers.UserDisplayName: Evargalo
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Answers.Text: What happens if a tournament spans more than one month?
Answers.UserDisplayName: itub
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Answers.Text: The classical way was to take it into account only after it has finished. There are some exceptions for long events like year-long team championships and a few top-level events.
Answers.UserDisplayName: Evargalo
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Answers.Text: Just one more thing. I'd guess that the websites that publish the 'live ratings' use method 1?
Answers.UserDisplayName: Myungjin Hyun
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Answers.Text: And I forgot to add this: I sometimes read articles that say that a player gained x points or lost y points in some *event*. Does that refer to the change in the rating corresponding to only that tournament?(Like you stated in your answer: gaining 50 points in one tournament or losing 100 in another.)
Answers.UserDisplayName: Myungjin Hyun
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Answers.Text: @HarryWeasley : no, the live rating websites use the Fide method, they do not adjust opponent's rating after each game nor each day. If you are 2300 and win 4 points on Monday, you are still 2300 for the calculations of Tuesday (not 2304). Two advantages: it is additive (if you won 30 points then lost 20 you will get +10) and it predicts the next published rating: your live rating on the morning of Dec the 1st is the same rating Fide will publish for you.
Answers.UserDisplayName: Evargalo
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Answers.Text: @Evargalo I'm confused: if they both use the same method, how are live ratings different from FIDE ratings?
Answers.UserDisplayName: Myungjin Hyun
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Answers.Text: You are 2300 on Nov 1 (k=10). You win against another 2300 on Nov 2. Your Fide-rating is still 2300 but your live rating is 2305. You draw against a 2450 player on Nov 3. We calculate your gain by considering you are 2300 (not 2305), your Fide-rating is still 2300 but your live rating is now 2307. If you don't play anymore until Dec 1, your Fide rating at that point will become 2307.
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Answers.Text: @Evargalo Thanks a lot for being so patient and explaining the whole thing clearly! Sorry it took so long to reply, your comment hadn't loaded until recently! Thanks again (+1), and I've accepted your answer!
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Body: <p>I'm aware that the FIDE ratings list is only published once per month.  I'm interested in how often the ratings are recalculated internally to FIDE without being published.</p>
  
  <p>Are ratings adjusted match after match, or after every tournament? Even if the ratings are updated once a month, does FIDE count every match, or a whole tournament?</p>
  
  <h1>An example to make my point clear</h1>
  
  <p>Consider a three-player, single round robin tournament.</p>
  
  <p><strong>Player</strong> &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;  &nbsp; &nbsp; &nbsp; <strong>Elo</strong></p>
  
  <p>Roanin Novel  &nbsp;  &nbsp;    2798</p>
  
  <p>Rigi Hains   &nbsp; &nbsp;    &nbsp; &nbsp; &nbsp; 2745</p>
  
  <p>Dan H. Yvasin   &nbsp; &nbsp;      2784</p>
  
  <h1>Results</h1>
  
  <p><strong>Round 1:</strong> R. Novel (1) beat Rigi Hains (0)</p>
  
  <p><strong>Round 2:</strong> Rigi Hains (0.5) drew with D.H. Yvasin (0.5)</p>
  
  <p><strong>Round 3:</strong> D.H. Yvasin (1) drew with R. Novel (1.5)</p>
  
  <h2>My question</h2>
  
  <p>If FIDE was calculating the players' ratings, would it first update the players' ratings <strong>match by match</strong><sup>1</sup>, or would their rating be adjusted by <strong>counting the tournament as a whole?</strong><sup>2</sup></p>
  
  <p><sup>1</sup> In this case, rating changes after every match.</p>
  
  <p><sup>2</sup> Here we calculate the expected score of each player at the start of the tournament, and compare it with the <strong>final score only.</strong> No rating changes occur between matches.</p>
  
  <h2>The calculations (all assume K=10)</h2>
  
  <h3>Method 1 [Match by match] (Final ratings in bold)</h3>
  
  <ul>
  <li><p>After the first match, R. Novel is rated <em>2802.24</em> and Rigi is rated <em>2740.76.</em></p></li>
  <li><p>After the second match, Rigi is rated <strong>2741.38</strong> and Dan is rated <em>2783.38</em></p></li>
  <li><p>After the last match, Dan is rated <strong>2783.65</strong> and Novel is rated <strong>2801.97</strong></p></li>
  </ul>
  
  <h3>Method 2 [Whole tournament]</h3>
  
  <ol>
  <li><p>Roanin Novel</p>
  
  <ul>
  <li><p>Initial expected score = 1.096 </p></li>
  <li><p>Actual score = 1.5</p></li>
  <li><p>Hence, new rating = <strong>2802.04</strong></p></li>
  </ul></li>
  </ol>
  
  <hr>
  
  <ol start="2">
  <li><p>Rigi Hains </p>
  
  <ul>
  <li><p>Initial expected score = 0.868</p></li>
  <li><p>Actual score = 0.5</p></li>
  <li><p>Hence, new rating = <strong>2741.32</strong></p></li>
  </ul></li>
  </ol>
  
  <hr>
  
  <ol start="3">
  <li><p>Dan H. Yvasin</p>
  
  <ul>
  <li><p>Initial expected score = 1.036</p></li>
  <li><p>Actual score = 1.0</p></li>
  <li><p>Hence, new rating = <strong>2783.64</strong></p></li>
  </ul></li>
  </ol>
  
  <hr>
  
  <h3>Conclusion</h3>
  
  <ul>
  <li><p>In such a short tournament, there doesn't seem to be a significant difference in the results of the two methods, but maybe there <strong>could be one in a longer tournament</strong>.</p></li>
  <li><p>Which of them does FIDE use?</p></li>
  </ul>
  
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Comments.CreationDate: 2017-11-14T14:30:30.623Z
Comments.Text: Why was this downvoted? I'd be glad to know how to improve it!
Comments.UserDisplayName: Myungjin Hyun
Tags: <elo><fide>
Title: Are Elo ratings adjusted after each match, or after each tournament?
ThreadText: # Are Elo ratings adjusted after each match, or after each tournament?
  
  (Asked by: username_0 on 2017-11-13)
  
  I'm aware that the FIDE ratings list is only published once per month. I'm interested in how often the ratings are recalculated internally to FIDE without being published.
  
  Are ratings adjusted match after match, or after every tournament? Even if the ratings are updated once a month, does FIDE count every match, or a whole tournament?
  
  # An example to make my point clear
  
  Consider a three-player, single round robin tournament.
  
  **Player**                 **Elo**
  
  Roanin Novel     2798
  
  Rigi Hains           2745
  
  Dan H. Yvasin     2784
  
  # Results
  
  **Round 1:** R. Novel (1) beat Rigi Hains (0)
  
  **Round 2:** Rigi Hains (0.5) drew with D.H. Yvasin (0.5)
  
  **Round 3:** D.H. Yvasin (1) drew with R. Novel (1.5)
  
  ## My question
  
  If FIDE was calculating the players' ratings, would it first update the players' ratings **match by match**1, or would their rating be adjusted by **counting the tournament as a whole?**2
  
  1 In this case, rating changes after every match.
  
  2 Here we calculate the expected score of each player at the start of the tournament, and compare it with the **final score only.** No rating changes occur between matches.
  
  ## The calculations (all assume K=10)
  
  ### Method 1 [Match by match] (Final ratings in bold)
  
  * After the first match, R. Novel is rated *2802.24* and Rigi is rated *2740.76.*
  * After the second match, Rigi is rated **2741.38** and Dan is rated *2783.38*
  * After the last match, Dan is rated **2783.65** and Novel is rated **2801.97**
  
  ### Method 2 [Whole tournament]
  
  1. Roanin Novel
  
     * Initial expected score = 1.096
     * Actual score = 1.5
     * Hence, new rating = **2802.04**
  
  ---
  
  2. Rigi Hains
  
     * Initial expected score = 0.868
     * Actual score = 0.5
     * Hence, new rating = **2741.32**
  
  ---
  
  3. Dan H. Yvasin
  
     * Initial expected score = 1.036
     * Actual score = 1.0
     * Hence, new rating = **2783.64**
  
  ---
  
  ### Conclusion
  
  * In such a short tournament, there doesn't seem to be a significant difference in the results of the two methods, but maybe there **could be one in a longer tournament**.
  * Which of them does FIDE use?
  
  **Tags:** elo, fide
  
  > **Comments:**
  > **username_0**: Why was this downvoted? I'd be glad to know how to improve it!  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2017-11-13. Score: 21 | Accepted answer
  
  **Neither**
  
  Elo-ratings are not ajusted for calculation after each game, they are not adjusted after each tournament either. They are adjusted **each month**.
  
  For all games played during one month, each player is supposed to have his last published elo-rating. If I am 2300 on the 1st of November and we play together November the 29th, your rating will be calculated by considering that you have faced a 2300-player. Whether I have gained 50 points in a previous tournament from 5 to 12 of November, or lost 100 points from novermber 16 to 23, will only be relevant for my rating on December 1st, and for my opponents in December and thereafter.
  
  In your example, the second method applies. But there won't be any ajustment after the tournament if one of your three players plays another tournament within the same month.
  
  > **Comments:**
  > **username_0**: So for every match that month, your expected score will be calculated assuming you are rated 2300 throughout the month. The grand total of all changes plus your old rating adds up to your new rating next month. Right? A bit like method 2, but over a whole month?  
  > **username_1**: Absolutely. Also for calculating norms, btw.  
  > **username_0**: Um, I'm not well-versed with such terms...a norm is something to do with IM and GM titles, right?  
  > **username_1**: @HarryWeasley : yes, that's a step into becoming WIM / WGM / IM / IGM  
  > **username_2**: What happens if a tournament spans more than one month?  
  > **username_1**: The classical way was to take it into account only after it has finished. There are some exceptions for long events like year-long team championships and a few top-level events.  
  > **username_0**: Just one more thing. I'd guess that the websites that publish the 'live ratings' use method 1?  
  > **username_0**: And I forgot to add this: I sometimes read articles that say that a player gained x points or lost y points in some *event*. Does that refer to the change in the rating corresponding to only that tournament?(Like you stated in your answer: gaining 50 points in one tournament or losing 100 in another.)  
  > **username_1**: @HarryWeasley : no, the live rating websites use the Fide method, they do not adjust opponent's rating after each game nor each day. If you are 2300 and win 4 points on Monday, you are still 2300 for the calculations of Tuesday (not 2304). Two advantages: it is additive (if you won 30 points then lost 20 you will get +10) and it predicts the next published rating: your live rating on the morning of Dec the 1st is the same rating Fide will publish for you.  
  > **username_0**: @username_1 I'm confused: if they both use the same method, how are live ratings different from FIDE ratings?  
  > **username_1**: You are 2300 on Nov 1 (k=10). You win against another 2300 on Nov 2. Your Fide-rating is still 2300 but your live rating is 2305. You draw against a 2450 player on Nov 3. We calculate your gain by considering you are 2300 (not 2305), your Fide-rating is still 2300 but your live rating is now 2307. If you don't play anymore until Dec 1, your Fide rating at that point will become 2307.  
  > **username_0**: @username_1 Thanks a lot for being so patient and explaining the whole thing clearly! Sorry it took so long to reply, your comment hadn't loaded until recently! Thanks again (+1), and I've accepted your answer!  
  
  ---
  
  