17-07-2003 12:42									#1
	[Attempt at] New PBEM rating system - continued Support Apolyton buy from Amazon

hi

i dont know how to get the original thread (here: http://apolyton.net/forums/showthre...&threadid=75637) out of the archive and i cant post there anymore so i just opened a new thread.

so here are the news:
last night i couldnt sleep... and guess what i did !
i started work on a rating system that would work for n>2 players while still retaining most of the characteristics of the ELO system that is used for 2 player games in Magic The Gathering and Chess rankings.

i'll try to stay at it. its roughly complete now. a few problems have to be sorted out still, but so far they seem managable to me.

also, im looking for a way to implement the ranking list in an Excel sheet as simple and automatic as possible.
for that purpose i also had some enlightenments, but problems remain here too.

if some CTP playing Excel guru happens to read this, please email to me at mathemagician@gmx.de. im sure i will have some questions during the next days and weeks.

	17-07-2003 12:43									#2
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ahhh, i finally could post this.
actually, it is already a day old by now and i think ive got the excel stuff understood and solved quite okay (though not tested yet).
still, a guru would help.

	17-07-2003 15:15									#3
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I still maintain CTP is not chess nor is it Magic it is unique and would require a rankings system that addresses all the variables of this unique game, chess and magic simply do not compare...

	17-07-2003 17:12									#4
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my system is meant to incorporate both the current (NOT past) in-game rankings of the players on the power graph of each game they're playing, and their score (=skill estimate) in the overall ranking table.

no system will seem perfect to everyone, but i think this ranking would have more significance than quinns' ladder right now..

	17-07-2003 17:30									#5
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A question to you all - who can count the changes that the various ratings systems have undergone, ever since the original idea came here?

I must say, though, that the MP community here has became much more interesting after the ratings were introduced. The Challenge Ladder is quite interesting though, IMHO.

	17-07-2003 17:33									#6
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quote: Originally posted by Solver A question to you all - who can count the changes that the various ratings systems have undergone, ever since the original idea came here?

mine wouldnt undergo any changes as it is perfect the way it is.

	17-07-2003 17:51									#7
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Now that's a pretty self-confident comment. I don't believe that anything can be perfect. Ouch, just noticed the smilie .

Seriously, though, I think our ratings have been through a very high number of changes. Where are the current PBEM ratings anyway, eh?

	17-07-2003 17:54									#8
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quote: Originally posted by Solver Now that's a pretty self-confident comment. I don't believe that anything can be perfect. Ouch, just noticed the smilie .

seriously, i think that by the time i got this system done, it would be quite good. thats serious !

quote: Seriously, though, I think our ratings have been through a very high number of changes. Where are the current PBEM ratings anyway, eh?

nowhere ?
the question is where they could be !

	17-07-2003 18:01									#9
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Good, yes, possibly, but not perfect .

Well, there might very well be a reason why the PBEM ratings are no longer here the way they were before. You are relatively new here, so you don't remember how big and good they were, say, at a point 2 years ago.

Both the WTC ratings used, as well as the more simple 10% formulae were good, and yet none of these rating systems have a big visible presence now... there has to be a reason, doesn't there?

I believe that, one of the main reason for that were the time constraints. With about 50 active rated players engaged in a few dozen PBEM games, there was quite a deal of results to proceed under the calculations to get the new ratings - that takes time. And while a few people have, at different points in time, expressed a desire to write a program that would simplify the job, unfortunately, it never happened.

I'll take this chance and yet again say big thanks to Quinns, Gavrushka, Blackice and other people who had the devotion to manage the ratings.

It might be my nostalgia, but this is what I would see as the best way:

Returning the PBEM ratings as they originally were, with minor tweaks possibly, using the old tennis formulae (that are rather simple, actually), but this time finally using a decent program to keep track of players and do the calculations, so that all the job would just take a few minutes, feeding ratings to the program and getting the result.

	17-07-2003 18:02									#10
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Toss out a formula so we can see.

Do to personality conflicts, mass hysteria and partisan politics the current system was folded.

IMHO it was not perfect but did address PBEM as a unique game far better than the old one. Actually I was not the only one to think that way.

I main problem was finding the time to do it. I have since found a program that would automate the calculations.

back to finding the time....

	17-07-2003 18:08									#11
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Pete, what program have you found?

And Blackice also just proves my point - the rating system was, erm, postponed or cancelled mainly not because of its drawbacks as a system - the main problems were time and some personal conflicts among the members. Both the tennis and 10% formulae worked fine, the former being my personal preferrence.

If only the few remaining active CtP players could stand out without conflicts...

	17-07-2003 18:14									#12
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quote: Originally posted by blackice Toss out a formula so we can see.

are you addressing me here ?

quote: IMHO it was not perfect but did address PBEM as a unique game far better than the old one. Actually I was not the only one to think that way.

i noticed a lot of people around here just say 'the old' and 'the new' system. could you please be more precise, e.g. by mentioning a key aspect of the system you are referring to ?

quote: I main problem was finding the time to do it. I have since found a program that would automate the calculations.

which one ?
i believe excel could do as well...

	17-07-2003 18:15									#13
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quote: Returning the PBEM ratings as they originally were, with minor tweaks possibly, using the old tennis formulae

CTP is not tennis either... The system could not be fixed it was tried.

The new system on the other hand was new and needed a few minor tweeks. It was a proven system made for CTP.

	17-07-2003 18:24									#14
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Mathe, Excel definitely doesn't cut it. Yes, it's a decrease in time, but still, you have to manually keep track of the players, manually enter their ratings, and such. The idea for a perfect program would be just one where you select names of players, order them by their power graph settings, then the program fetches their current ratings from the database, does the calculations, and there you go.

Blackice - the tennis system was fine. CtP is not tennis, but the formulae were very well designed to work with other games, too. I remember that some people who were not too good with maths got scared of the formulas, but they seemed very easy to me once I took a look. The system had drawbacks, but they were mainly fixed. Although, I remember that you were probably the strongest one of those against this system.

The "new" system was also good, being designed to simplify the formulas somewhat, and make it easier, although it still took time. While it was balanced enough and rather good... I did at times feel it was too simple.

Mathe, the old Tennis system merely used same formulas as Tennis does to calculate ratings adjustements by powergraph, where the key aspect was the difference in ratings between players. That is, a high rated player got little by beating a much lower rated players, but a low rated player got a lot by beating a highly rated player. For the record, very similar formulae are used in many RTS matchmaking systems.

The new system was more dependant on the player count in a game, and it was, well, simpler, depending largely on certain constant numbers, but I don't exactly remember off the top off my head.

	17-07-2003 18:24									#15
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quote: are you addressing me here ?

yes

Some of us have

I think Math's suggestion some time back of limiting the 10% or making it static per game would have fixed the systems one minor flaw. Mind you I did not see it as a flaw. The more games you play the more rankings you should have.

The change was contemplated to hopefully bring the community together, back to partisan politics....

Excel can do it not problem but it still requires manual input by a member or several volunteers. This program is incorporated into the HTML or PHP coding.

The players enter them then it automatically adjusts the rankings.

All the players do then is post the information for confirmation reasons.

Personally I have aways agreed with combining PG and score as a more realistic approach to CTP.

	17-07-2003 18:28									#16
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See, Pete, I believe that it should NOT anyway continue till a fully developed program is available - one that stores ratings in a database, etc. I think that at one time I even wanted to write it, but for some reason did not, oh whatever.

And, I disagree that score should be taken in account, I pretty much believe that the PG provides a fair indiciation of how is a player doing in a game - although, well, score does have its upsides. I'm not so cathegoric here.

Nonetheless, I still believe that the Tennis system, when used, was better. Another indication of it is, that it worked for longer than the 10% system did. Tennis system worked ever since the ratings were originally invented, and all the way till a bit after Quinns took his long break from Apolyton.

Again, I repeat - should there be a program that does it, I would be very glad to again reinstate the Tennis systems.

And, in those times, the ratings got published in CtP news all the time, etc, the tennis system got more recognition from players.

	17-07-2003 18:31									#17
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Solver it was not the formulas most disliked, it was the fact one player playing one game and winning could sew up top spot endlessly. The "Clair factor" which you and I both know most all hated that aspect.

Color it how you will that was the bigest flaw in the system and it could not be corrected. You want multi game participation that system was not the way to get it. Keeping people in games nope it did not do that either... What was good about either of those things?


That while the rest of us played 20 games and bounced up and down the rankings with no end in sight. No consideration for the unique aspects of CTP, land, diplomacy, etc. People quiting games because of land position it was endless...

A top player could lose 20 spots simply because of land. So we made up more rules upon rules just to get the system working. That in itself marks a flawed system, we hit what a full page of rules and more were to added just to get the system to work.

The new system needed minor rules not endless streams of them.

BTW not to get into this again but the tennis ranking system is not very well liked in most forums, let alone the tennis circle.

Actually not so much player count as it could use 2 to infinity as players. It was more dependant on score and pg as I understand it from the originator at GL. The percentages paid out were averages of the percentage if you conbine the score and pg totals vs the other players. IE skill... I will point out it was designed for CTP not chess, tennis, or any other non-related game.

They also took into concideration landscape as the game progressed.

Designed for CTP, simple, more fair, less rules and more game participation were the keys reason's for the change. Up until partisan politics, personalities got way out of hand most liked the new system.

I threw up my hands in dismay at the childishness of the whole affair. It became not worth the effort, rather than seeing it as a change for the better it became a call to arms for the few partisans to bring the whole thing down. enough said...

Last edited by blackice on 17-07-2003 at 18:49

	17-07-2003 18:35									#18
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alright,

first of all, i think Excel can do the calculations.
all i would need to enter is the position of each player in the latest power graph of the corresponding game.

assume, ratings are re-calculated every 10 turns, all i would need is someone telling me who is ranked where on the power graph (counting only the human players).

i enter that into excel and voila: the new results.

i admit, i havent done it yet, but i thought about it, and i dont see any relevant lacks in the excel logic.

only a sorting algorithm for the final table i havent found yet, but im sure that could easily be done manually if the ranking is updated, say twice per month.

	17-07-2003 18:38									#19
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I agree that one player being well ahead in a game was the biggest flaw of tennis rating, but that is, IMO, rather easily fixed. I don't want to go into detailed maths here now, but by adding another variable to the formula, which indicates the turn number, this could be balanced. That is, the player atop of power graph gets less and less rating boost, while the loser also is taking less of a loss in the rating. When I have the time, I can do the maths and see what the coefficients would have to be for it to be reasonably balanced.

See, there will always be people disliking a certain ratings system, but there's a good reason the tennis ones are used so widely, and it's that they work fairly well - with flaws, but so does everything else.

Therefore, I would be rather willing to contribute my thoughts to adjust the tennis rating formulas, but they were, IMO, preferrable.

It's getting the players back here again that would be problematic.

	17-07-2003 18:42									#20
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quote: Originally posted by Mathemagician alright, first of all, i think Excel can do the calculations. all i would need to enter is the position of each player in the latest power graph of the corresponding game. assume, ratings are re-calculated every 10 turns, all i would need is someone telling me who is ranked where on the power graph (counting only the human players). i enter that into excel and voila: the new results. i admit, i havent done it yet, but i thought about it, and i dont see any relevant lacks in the excel logic. only a sorting algorithm for the final table i havent found yet, but im sure that could easily be done manually if the ranking is updated, say twice per month.

In this regard, you better trust me. Excel does not work good enough, and I say that as someone who has been doing that stuff with Excel. Firstly, entering and doing all that stuff still takes certain time, and it's easier to make a mistake. And, it takes enough time for you not to look forward to doing it all. Excel won't keep you ratings of players unless you work on it a lot, which is a pain in the butt.

A program that worked, though, would easily do it all so quick that the ratings could even be updated every week, provided that there are enough rated games - and the last time they were.

I speak of experience here.

	17-07-2003 18:47									#21
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now to the system itself.
i was hoping to not have to explain it in detail.

here is an overview:

some of you might know the ELO system i referred to above (that as i know is used at least for the Magic world ranking, there including 10,000s of players).
no idea why it is called ELO. anyway...

the formula there, for each finished two player game, is:

new score = old score + K-factor * {result - 1 / (1 + 10^((own old score - opponents old score)/400)) }

i hope all the brackets are right and understandable.

K-factor
simply weighs the importance of the tournament the match was played for. it therefore is the maximum number of points you theoretically could gain or lose in the game.
for equally scored players, the winner will take K/2 points and the loser will lose K/2 points.

result
is the result of the match being played.
1 if you win
1/2 for a draw
0 if you lose

the complicated thing in "(result - complicated thing)"
thus gives a value from -1 to +1 depending on the score (think:skill) of both players.
this is NOT the in-game score, its the ranking score of those players in the global ranking system.
the whole bracket then gives a value from -1 to +1, meaning you can lose 100% of K (for a -1) or win 100% of K (for a +1) or something in between.

the main problem was to replaced the difference of two scores in a two player game by something equivalent in a multi-player game without losing the important characteristics of the system.
one of these characteristics was that the complicated part of the bracket, calculated for player A would always be the negative of that for player B, so each player would gain what the other loses.
thus the whole ranking system would not lose or gain any points.

i now simplified this last bracket part in a somewhat more linear way,
mainly by using r(i) and s(i), so the bracket part for each player would be ( r(i) - s(i) ).
actually, the r(i) should be r (rank(i)) where i is the index of a specific player.

the r(i) would sum up to 1, like in the original.

im still working on the s(i), but what is for sure is that they depend on the skills (score) of ALL participating players in the game and of course in a seperate way, on the score of the player with the index i.

..

so much... want more ?

	17-07-2003 18:49									#22
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quote: Originally posted by Solver In this regard, you better trust me. Excel does not work good enough, and I say that as someone who has been doing that stuff with Excel.

i see that as a challenge to prove you wrong.

	17-07-2003 18:54									#23
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I see. I'm good at maths, so you can hardly scare me with those big long formulas. And I can say that to work effectively in games with many players, the formula would need to undergo some changes.

quote: one of these characteristics was that the complicated part of the bracket, calculated for player A would always be the negative of that for player B, so each player would gain what the other loses.

I'll take your word for it... don't want to check it now, and that's another thing that I dislike. IMHO, that's not good for a game such as CtP.

And finally, the whole K-factor is wrong here. I know how it's right in Chess and such games, but we can't do it here... unless we actually make K some constant value here.

So, for now, you don't have me convinced, I believe that the system would only work reasonably for 1v1.

	17-07-2003 18:55									#24
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quote: i see that as a challenge to prove you wrong.

Try to. Give me a fully automated program and let's see if you can do it quicker with Excel than I can with a program written solely for the purpose of calculating these ratings .

Just hardcode the whatever formulas, tennis, 10% or ELO into the program, and there it is .

	17-07-2003 18:56									#25
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quote: rather easily fixed.

It was with the new system, you see the new system had that built into it.....

No need to fix it the new system did all that and more...

No time to view it now Math, have to go to work thanks I will have time later though.

Drawing people back Solver will take a group effort if partisan politics and iron fisting were to contniue, well I agree it will be a problem.

You see some think for the community as a community not power or politics...

In the community poll most prefered the new system, remember?

	17-07-2003 19:01									#26
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thats why im still working on the formula.

i didnt say i want only the bracket changed, i said it was the hardest part.

K is somewhat irrelevant. i dont know what you think is wrong about it, but it simply scales the (-1,+1) interval to the desired length in which the score scale is.

so far, i didnt completely check this system, but i can say that at least the score the weakest player will win if he wins the game is equal to the score the strongest player will lose if he loses the game.
me thinks that also all the scores some up to 0, but i havent mathematically proven it yet.

and what exactly was the thing you disliked about that last quote, solver ?
that the whole score wouldnt change ? why not, it gives the whole ranking the (in my eyes) ideal characteristic that you CAN win more points by playing more games, but also increase your risk of losing more points. plus, the higher you are on the ranking list, the higher the average place you need to make in your games, or simply put, the higher the percentage of games you need to 'win' in order to keep your ranking position.

	17-07-2003 19:04									#27
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Drawing people back is possible, though, with an effort from the sane and old-time members of the community.

As said, I have nothing against the 10% system, I just believe it not being better than the old one. But, of course, I am rather democratic. Many people do, though, I believe, not clearly enough see the good and bad points of each.

I do, for instance, trust that the rating system with tennis formulae provided better adjustements to ratings overall, the tables being more dynamic and interesting. But this is just my opinion.

And one thing Pete, I'm sorry to remind you, but you were also involved in some of that iron fisting, and what not .

Well, I admit that I *may be* biased towards the tennis system somewhat, too, for reasons that people who've been around as long as you can probably understand.

	17-07-2003 19:06									#28
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about the politics/poll, i think first we should sort out which characteristics the miscellaneous systems would have and then everyone, also the mathematically, less inclined, can vote on the system they want, judging by desired characteristics.

some can check the mathematical statements, others might just trust them.

	17-07-2003 19:08									#29
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solver, could you please tell me more about this tennis system ?
was it the one gavrushka used that needed a hell of a lot of tables ?

did i mention my system, apart from more or less complicated equations , needs only the results, previous scores and number of players as input and directly puts it into the formula ?

	17-07-2003 19:09									#30
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Mathe, the thing I was disliked was exactly that, the losing players loses the amount of points the winner gets with a minus sign.

That is, |lost| = |won| , isn't correct, IMHO.

A player rated 1700 beats a 1610 player and both get the same adjustment to their ratings. It works fine, but in 1v1 games. In a 7 player CtP game, one player has 6 wins essentially, the next one 5 wins and 1 loss, and so on. Won't this formula give the winning player too big of an advantage over the others?