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Joined on 14 feb. 2001
Total posts: 1.964
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Couple ranking system
6. mars 2004 12:27
I think I agree in principle, that system based on ranks of others competing in the same event is probably the best. However I cannot imagine a formula to this. I would also like to see some difference between people in semi. ELO is based on individual comparisons between 2 people, while dance comps compare at the same time many couples. As I have said before - if anybody has a sensible formula - we are ready to implement it, even only to try it out. Very difficult point is - where to start from.I would suggest for example that all start 1 year ago from 1000 points each and scale for each comp is like 1/x, because difference between first and second place is bigger than between 17th and 18th.
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Joined on 12 ágú. 2003
Total posts: 84
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Couple ranking system
7. mars 2004 15:07
Ah, starting it... hadn't thought of that.
I think you need to "prime" it somehow. It might be necessary to run the last years results through several times to get a starting point. Each time you'll get more accurate rankings at competitions...
I think the idea of rewarding places by 1/x is great (or a similar distribution). If you have all the results in your database maybe you can set it up and play with the parameters a bit until it is stable... I think a potential problem is to make sure scores don't "inflate" or "deflate" over the years if they are self-referencing.
Anyway, i'd love to see a system like this tried, even if imperfectly, it can always be optimised!
Robin
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Joined on 03 mar. 2004
Total posts: 5
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Couple ranking system
8. mars 2004 11:54
If a self-referential formula is used, terms involving 1/x will probably inflate over repeated iterations (it is a "non-convergent" series I vaguely recall) how about
x
1/2 ("1 divided by 2 to the power of x) ?
(I would suggest 1/exp(x) except this isn't good without a calculator!)
- The artist formerly known as n/a.
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Joined on 12 ágú. 2003
Total posts: 84
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Couple ranking system
8. mars 2004 13:57
Wow, this is getting very mathematical for a dance-forum ;).
I think whether inflation occurs will depend on the total number of points given out. To prevent this, the number of points awarded in an event should be such that it maintains the average point score of all competitors.
E.g. if we say the top 5 results of each couple count towards their ranking, then the total points given out in one competition should be: Sum(all couples' scores)/5. The way these points are distributed will then determine the shape of the distribution of ranking points.
How difficult would it be to try some system on the results already in the database?
Robin
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Joined on 03 mar. 2004
Total posts: 5
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Couple ranking system
10. mars 2004 08:17
Hi Robin,
Sounds like you are talking about the mathematical term "normalisation". I'm still thinking about appropriate, simple formulae. "Admin"'s suggestion of an ELO type scoring system would, for n couples lead to n multiplied by (n-1) separate calculations (i.e. time consuming). "Admin" would probably agree the optimum would be one calculation per couple and a calculation for the weight of the competition whose length/difficulty is only linearly dependant on the number of couples competing. Woops! Anyone still awake ?
Just one more point for now -
It's not necessary to input historical data really is it ?
If everyone is given the same initial score, differences would appear, quickly (I believe), within a few events. Rankings could be published after a few events when these differences become apparent.
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Joined on 12 ágú. 2003
Total posts: 84
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Couple ranking system
10. mars 2004 11:26
I don't think n-1 calculations per dancer would be particularly prohibitive. Even for the largest of events with 300 participants (ie blackpool), this would mean only 90,000 calculations, i'm not suggesting anybody should do them by hand!
As for historical data. It would be very easy to include as Dancesportinfo seems to have a fairly large (though not comprehensive) database of results. All of these could be used, and it would be nice if a league table started with a meaningful order!
Anyway, i don't know how much time Zbyszek has on his hands, but judging by this website (and assuming it's mostly written by himself) I would imagine that any system could be implemented fairly easily.
If it's possible to implement them in the space of a few hours, maybe we could just try a few version on the existing results data set and see which results in the most "senisble" ranking. So to summarise possibilities:
- ELO-system (treat each competition as lots of 1:1 match ups, each person you end up higher than you have "beaten")
- normalised points system as discussed previously (points given out are proportional to 1/(a^n) (with being some coefficient around 1.2 or so) and normalised to the total number of points of all competitors (divided the maximum number of competitions couning towards a league)
- fixed points schedule with 4 categories. The category is chosen based on the number of total ranking points entered, or similar objective criteria.
My prediction is that i will like the outcome of the ELO system best, but a fixed schedule will be the most transparent, with option B being a compromise between transparency and accuracy...
Zbyszek, do you think it would be difficult to try? Is there anyway i (or others) could help?
Robin
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Joined on 12 nóv. 2003
Total posts: 41
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Couple ranking system
10. mars 2004 11:52
Hi Robin,
I have been following these deliberations closely, but unfortunately the maths of it all is way beyond me! However I am willing to offer my help in getting a workable system up and running (as long as someone explains to me clearly what to do!). Alun, who has been writing long and complicated suggested formulae on this topic, is a friend of mine - maybe we could all work together to trial a possible system?
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Joined on 06 jan. 2004
Total posts: 1
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Couple ranking system
10. mars 2004 14:34
I've only just come across this topic. I think it would be a brilliant idea to have a UK Sunday circuit rankings/results. I have heard several fellow competitors say that they wish it could be done. Whilst I'm about it - a Dance News type magazine for the UK sunday circuiters would also be great - for any entrepreneurs out there.
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Joined on 14 feb. 2001
Total posts: 1.964
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Couple ranking system
10. mars 2004 17:59
OK - after exchanging some Emails with Robin - I am trying to implement ELO system. Work is in progress and hopefully in couple of days I will be able to present first results.
There are some big problems, however (only indirectly linked to ranking system):
1. We do not have enough results for 'Sunday circuit' dancers. We mostly have upper positions (as you probably know). Any help with getting results would be appreciated
2. We desperately need some help with keeping up with results - any volunteers?? We will tell you what format of data we need for easier input - At the moment 95% of the time is 'data clearing' (mainly correcting spelling)
3. To be frank - we need to generate some income. Controtex is financing our work for over a year. Maybe you can help us to find sponsors, advertisers or people wishing to have websites with us
I will let you know when provisional (D)ELO :) is ready.
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Joined on 12 nóv. 2003
Total posts: 41
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Couple ranking system
10. mars 2004 18:17
Zbyszek, this is really good news. Thanks for agreeing to give it a chance. I know that Alun is working on suggestions regarding the ELO system which he also thinks is the best way forward and he will be in touch with you as soon as possible.
As far as reporting of results is concerned, I am willing to help as much as I can. Alun and I tend to go to comps in the south east with a few bigger comps thrown in. I think ideally we should make contact with comp organisers in advance so that they know we will be looking to get hold of results to pass on to you. Just let me know exactly how you need the information to be presented and I will do whatever I can to get this going from our end. Obviously it will take a lot of effort from us to get this system started, but I think that once people cotton on to the fact that they can earn points for competing it will encourage them to support more comps and the promoters will soon see the benefits of helping us out by forwarding results.
I await the next instalment eagerly!
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