Don't Understand Grading Calculation

General discussions about grading.
Roger de Coverly
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Re: Don't Understand Grading Calculation

Post by Roger de Coverly » Thu Oct 24, 2019 2:03 pm

Chris Goodall wrote:
Thu Oct 24, 2019 12:13 pm

Is a grade of 0 supposed to represent the weakest person capable of playing a game under FIDE Laws, or a random move machine?
Neither. Both the Clarke scale and the Elo scale were essentially arbitrary with one of the objectives being to avoid negative grades or ratings. Back in the day, they would compare notes. On the usual conversions, Clarke's zero was higher than Elo's.

The underlying mathematical statistics of both systems makes an assumption that chess strength is stable if unknown. Arguably an assumption that breaks if you try to apply it to extremely weak players.

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Chris Goodall
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Re: Don't Understand Grading Calculation

Post by Chris Goodall » Thu Oct 24, 2019 5:34 pm

Roger de Coverly wrote:
Thu Oct 24, 2019 2:03 pm
The underlying mathematical statistics of both systems makes an assumption that chess strength is stable if unknown. Arguably an assumption that breaks if you try to apply it to extremely weak players.
When you say stable, are you talking low stdev that can drift, or high stdev with a stable mean?
Chris Goodall, formerly known as Chris Wardle. Northumbria League hand-cranker; ECF Grader for Bernicia and the NCCU.
Newcastle is not in Scotland!

MartinCarpenter
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Re: Don't Understand Grading Calculation

Post by MartinCarpenter » Thu Oct 24, 2019 10:12 pm

Depends how active people are.

What isn't really arguable is that 95% of club players hit a level fairly fast and then stick on it for a very long time. Fluctuations to and fro as life intervenes of course.

dejan_lekic
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Re: Don't Understand Grading Calculation

Post by dejan_lekic » Tue Dec 10, 2019 9:26 pm

Well, that would be the case with the current system, and that is precisely why we want to move to ELO or GLICKO-2 (I hope ECF people considered GLICKO when they discussed the new grading system). Also, it is highly unlikely (s)he will beat only children, no matter what division we talk about. - There are other possibilities too, like, for an example, one of those low-graded children beats him instead, because the ECF failed to grade that kid properly, which is another problem we face with ECF all the time...

I think one of the problems is that people are used to abuse the ECF system, and use its shortcomings to their advantage. I am sure many of people here saw that team captains estimated a player to 100ECF, and once the grades are out that player gets 160+ grade.

Finally, people need to get a grade somehow. Once I tought it is a good idea to have "grading tournaments" and disallow ungraded players in ECF tournaments and leagues, but it is time-consuming and it seems quite harsh.

NickFaulks
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Re: Don't Understand Grading Calculation

Post by NickFaulks » Tue Dec 10, 2019 9:38 pm

dejan_lekic wrote:
Tue Dec 10, 2019 9:26 pm
I hope ECF people considered GLICKO when they discussed the new grading system
That would certainly have justified the title of this thread.

dejan_lekic
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Re: Don't Understand Grading Calculation

Post by dejan_lekic » Tue Dec 10, 2019 9:47 pm

That would certainly have justified the title of this thread.
:) I should have been more precise - by "ECF people" I was referring to the people who work on the new grading...

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