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|\_ IECG Rating Rules, Version 1.7 May 27th, 1999
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I. General Principles
1. The IECG Rating Scheme is a numerical scheme, in which
percentage results can be exchanged into rating differences
and rating differences into percentage performance probabi-
lities. It is mainly based on the ICCF Rating Scheme.
2. The basis of the scheme is the normal probability distribution.
3. The performance probability is calculated by the formula
P(D) = 1/(1+10^(-D/400))
where
P(D) is the performance probability
D is the difference of the ratings of the two players.
4. The expected rating changes based on the percentage result is
given by
D(p) = -400 * log10((1-p)/p)
where
D(p) is the expected rating change
p is the percentage result of the player
and D(0) = -800 and D(1)= 800
5. The formulas used in I.4 and I.5 are good approximation of the
tables used by the ICCF.
6. The percentage result is calculated by
p = (2*W+D)/(2*N)
where
p is the percentage result
W is the number of wins in the rating period
D is the number of draws in the rating period
N is the number of finished games in the rating period.
II. Rating Period and Rating Method
1. The Rating Period is 2 months. The first period
of a year starts on January 1st.
2. The Rating List is published on the first weekend of every second month
on the IECG Webserver at http://www.iecg.org/ . At the same time
the representatives from the IECG Tournament Offices receive
a special version of the rating list.
3. For calculating the ratings, the opponents Tournament Entry Ratings,
which are valid on the day of the rating run, are used.
4. Ratings are calculated in batches. A batch is made of all
games of a player finished in the rating period. The batches
do not necessarily contain all results of a tournament.
5. The Rating List contains the following information:
a) Position on the list
b) Position in the players class
c) Players Membership Number
d) Players Name
e) Players Country
f) Players Rating
g) Players Tournament Entry Rating (TER)
h) No of rated games of the player with the new scheme
i) Players Win-Draw-Loss Statistics
III. Established, Provisional and Starting Ratings, Performance
Differences of Opponents Ratings.
1. A player has an established rating, if he/she has finished
at least 15 games, otherwise his/her rating is called
provisional.
2. New players get a starting rating, established by a method
explained in section VII.
3. Provisional ratings are not published until at least six
games are accepted for rating.
4. The Rating Office can publish intermediate ratings on the first
weekend of the months where no rating is calculated. The published
Performance is calculated as if the rating period had ended
on this particular date. However, the tournament entry rating is
unchanged.
5. The performance is not calculated for the first six games,
i. e. it is treated as the provisional rating.
6. To determine which Class or Quad Tournament a Player may
enter or in which IECG Cup Group a player may start, his/her
Tournament Entry Rating is used. The only exception are
qualifications according to the corresponding tournament
rules.
7. The Tournament Entry Rating (TER) is equal to the Established
Rating in the last published Rating List. For Provisional
Ratings, the TER is equal to the Starting Rating, unless at
least 10 games are finished.
8. To keep the influence of largely different ratings small for the
preliminary (and established) ratings, a rating cut-off is used.
Anytime the difference is larger than 400 points, the opponents
rating is treated as being 400 points (one tournament class)
higher/lower than the players rating.
IV. Calculation, Publishing and Use of the Provisional Rating
1. The Provisional Rating is calculated by
Rp = Rc + D(p)*F
where
Rp Provisional Rating
Rc Average of the opponents tournament entry ratings
D(p) Expected rating change based on I.4
F A Correction factor given by
F = -2*p*p+2*p+0.5
2. The provisional rating is published for the first time after
six games are finished.
3. (deleted)
4. If at least 15 games are finished, the provisional rating
becomes an established rating. This promotion can take place
only at the end of a rating period. Any additional games are
treated as results for the provisional ratings as well.
V. Calculation of Established Ratings
1. For each finished game the rating change is calculated by
dR = k*(W-We)
where
dR Rating change
W True game result (win 1, draw 1/2)
We Expected result (calculated following V.2.)
k Development coefficient (see V.3.)
2. The expected result We is calculated using I.3. with the
rating difference of the two opponents. It is called P(D) in
section I.3.
3. The development coefficient is a stabilisation factor and is
given by
k = r*p
with
r = 10 if Ro >= 2400
r = 70-Ro/40 if 2000 < Ro < 2400
r = 20 if Ro<= 2000
and
p = 1 if Pn >=80
P = 1.4-Pn/200 if 30 < Pn < 80
P = 1.25 if 15 < Pn <= 30
P = 1.5 if Pn <= 15
where
Ro is the Rating from the previous rating list
Pn is the number of all rated games upto the previous
rating list.
4. The next rating is calculated by
Rn = Ro + SUM(dR)
where
Rn new rating of the player
Ro old rating of the player
SUM(dR) Sum of all rating changes as calculated in V.1.
for each game.
This whole paragraph has been taken from the ICCF regulations
with only minor changes.
VI. Sequence of calculation
1. There is no special calculation sequence required, since
- all ratings are taken out of the previous list
- no unrated players exist in the rating list (see VII)
VII. New Players
1. New Players with an established ICCF rating will be treated
as having an established IECG rating, since the IECG rating
calculation is derived from the ICCF system.
2. New Players with an established rating from a different
organization or with a provisional ICCF rating do get this
rating as his Starting Rating. If required the national
rating will be converted into an FIDE rating with the
appropriate conversion rule. No plus or minus points
relative to the IECG Rating are used. The established rating
must be based on at least six games.
3. New players without a rating will get a Starting Rating of
800 or a rating estimated by the tutor. This rating should not
exceed 1700 points.
VIII. Forfeits, Withdrawals, Inactive Players
1. Forfeits based on arbiter decision (claim on time, etc)
are rated as normal finished games. This is normally a
single event with an individual player.
2. Withdrawals from tournaments are generally not rated
depending on the tournament secretary decision.
3. The remaining players may request an adjudication of the
game to gain rating points. The adjudication is binding.
Based on the result of the adjudication the rating is
updated. However, the game is treated as a win in the
score tables.
Note: This regulation can lead to a loss of rating points
of the remaining player, if the adjudication result is
not a win, but a draw or even a loss!
4. A player is called inactive, if he/she is not playing a
game in a rating period.
5. Inactive players are removed from the rating list after
being inactive for one year. Their rating keeps valid for
another four years. Then the player is deleted from the
database.
6. If an inactive player becomes active, his/her rating from
the database is still used.
IX. Transfer regulations from the Old to the New IECG Rating
Scheme, Inauguration of the Scheme
1. All IECG games started before June 1st, 1996 have to be
rated with the old scheme, if they are finished before
January 1st, 1997.
2. From January 1st, 1997 all ratings are calculated following
this document.
3. All games started after August 1st, 1996, have to be cal-
culated following this document.
4. This scheme comes into operation commencing January 1st for
all games after the reorganization. Games finished before
this date are treated as being finished afterwards.
5. With the inauguration of this document the following steps
are taken:
a) All established IECG ratings based on at least 15 games
are transferred to the new rating scheme as established
ratings.
b) All established IECG ratings based on less than 15 games
are used as a starting rating. If more than 5 games are finished,
the opponents average for the provisional rating is calculated
following IV.1.
c) All provisional ratings are left unchanged and stay
provisional until 15 games are finished.
d) All starting ratings are checked if the players does
have an ICCF rating. This ICCF rating replaces the
IECG rating, if it is higher, and is used as an
established rating.
e) All players who have won an old Class M tournament (#001 to #013)
before January 1st, 1997 are rewarded an established rating for
this extraordinary result.
X. Contacts
1. All results must be sent to the corresponding Tournament
Secretary.
2. All questions concerning the table should be send to the
Rating Official.
3. The current Rating Official is Dr Ortwin Paetzold
(opaetzol@iname.de).
The IECG Council
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Last updated : May 27th, 1999
Update History:
Date Description of Changes
Version 1.0 Jan 1st, 1997 First Release of the IECG Rating
Rules
Version 1.1 Mar 3rd, 1997 Section VII.4: addendum to sentence
4 about the correction factor. The
sentence now reads:
"The Starting Rating is calcu-
lated according to IV.1, but with an
correction factor of F=1."
Section III.3 is disabled until real
automatic routines working with mail
are available
Section III.7: The number of games
required for a change of the Starting
Rating is increased to 10, as has been
originally discussed and decided in
the IECG Council Mailing List in
October 1996.
Version 1.2 May 29th, 1997 Section IX.5 changed: part a) added, part
b) changed, it read:
"All established IECG ratings are used
as a starting rating."
Version 1.3 June 1st, 1997 Section III.7 changed, it read
"The Tournament Entry Rating is equal to the
Rating in the last published Rating List, if
more than 10 games are played, otherwise it
is equal to the Starting Rating."
The new version explains the use in more detail.
Section IV.3 has been deleted, since it is covered
by section III.7.
Version 1.3.1 July 13th, 1997 Correction of the formula in I.6
Version 1.4 December 30th, 1997 Addendum to VII.4, added the sentence with the
Starting Rating boundaries.
Deletion of R Steinkellners Web-Server URL in II.3
Version 1.5 April 5th, 1998 Section III.8 added to keep top players with preliminary
ratings playing in the Cup.
Section IX.5.b) extended by the last sentence.
Section IX.5.e) added.
Version 1.6 September 27th, 1998 Comment on Discontinuation of Rating Tournaments.
Version 1.7 May 27th, 1999 Adaptation of the Rules to current Practice (length of
Rating Period, Format of Rating List, Webserver etc.)
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