ITTF has changed the Table Tennis World Ranking System. The fan around the world has various opinions. Some supports, other find the new system has some flaws. Here, I want to present one of the most scientific and well-researched ranking systems for table tennis “Rating Central”.
Skip3119 on MyTableTennis.net said:
“It appears that Dr. Marcus is waiting for the ITTF’s ever-changing system to stabilize then he will spend lots of his precious time to rewrite his scraper program to capture the data.
As the ITTF’s new ranking system screws up what “ranking” is really supposed to mean – a higher ranked player is now not necessarily a stronger player than a lower ranked one. In the mean time ITTF got rid of “rating point” record for each player and made head-to-head record unavailable.
Under these circumstances, the Ratings Central just becomes more informative and more valuable to the world-wide TT fans than ever.”
David J. Marcus moved to Massachusetts to attend graduate school at MIT and received the Ph.D. in Mathematics (Probability).
He was president of the MIT Table Tennis Club for many years. Currently, He is one of the organizers of the Boston Table Tennis Center.
He is the creator of a sophisticated table tennis rating system that powers Ratings Central, a website, and real-time rating system that he built, maintain, and develop, along with his colleague Sean O’Neill (American national table tennis player and coach).
David J. Marcus, Ph.D.
What Is Ratings Central?
Ratings Central is a state-of-the-art, fully automated, the online rating system that is very accurate, is open to anyone anywhere, is extremely easy for event directors to use, and provides extensive, detailed, accessible information on events, matches, results, ratings, and rankings.
Why is Rating Central so accurate?
Ratings Central uses a sophisticated rating algorithm (developed by David J. Marcus, Ph.D.) that fairly and accurately rates all players, from world-class to beginner, from those who compete regularly to those who compete infrequently. The algorithm was originally developed at the request of USATT, but despite being dramatically better than the USATT rating system, USATT has not adopted it (due to inertia and politics).
The core of Rating Central based on the mathematical laws “Distribution and probability-of-upset function”. Read more here.
Why didn’t Rating Centrals update the latest results of ITTF?
About a year ago, ITTF unveiled their wonderful new site. It looked all cool and was probably written in AngularJS. However, it was hard to view the draw sheets: you could only see one match at a time.
You wonder who thought that was a good idea. Probably other things were messed up, too. However, they left the old site up, so you could still find the results there. And they soon added links from the new site to the draw sheets on the old site.
ITTF has changed the plan
In October, they sent out this press release:
So, another disastrous IT project bites the dust. At that point, the old site disappeared and the new site stopped even having its one match at a time results. Now, it only has PDFs of the draw sheets.
Scraping the PDFs wouldn’t be a lot of fun, and it sounds like ITTF will be trying to make changes to the site. We’ve seen a couple of other sites that have ITTF data in a more usable format, but we don’t know how official they are or how they get their data. So, I’m waiting to see if things stabilize before spending a lot of time trying to rewrite my scraper to grab data off the current site.
We have no contacts in ITTF, so if anyone knows anything, feel free to pass it on. I have no idea if ITTF intentionally makes the data hard to get or it didn’t occur to them that people would like to be able to get the data.
David explained on MYTT:
It took some effort to write the scraper program. But, it generally only took me about five minutes to submit each event (except when ITTF did something weird with the data, like had matches where the winner was neither of the players or made up new event codes).
Why didn’t USATT adopt the Rate Central system?
They mostly ignored us.
The original project was suggested by Sean and the USATT Ratings Committee. Before spending 2000 hours developing a new system, I wanted some indication that it was wanted and would be adopted.
Some board members seemed supportive. But, words are cheap. I said that to do the research and development, I’d need some better computing resources (remember, this was long ago when computers were primitive). I said USATT should pay for a decent computer and software that I could use for the project; this would cost around $5,000. I would contribute the 2000 hours
The board declined. But I’m pretty sure it was because the Executive Director didn’t want to spend the money. The Executive Director then said we could get a grant from the USOC. Perhaps foolishly, I agreed, and we did that. Skip ahead a couple of years, and the system is ready and the Rating Committee recommends USATT adopt it.
By this time, the few somewhat-friendly people on the board had been voted out, and the board was full of nutty people. We attended the board meeting where it was decided whether to adopt the new system. The discussion was completely nutty with board members saying things that were ridiculous (with ridiculous PowerPoint presentations to back them up). I think the vote was 7-5 against.
I have spent a lot of time
In retrospect, I’m happy to not be involved with USATT. They are very hard to work with. Tangential to Ratings Central is Zermelo, my tournament software. This supports USATT tournaments. Twice in the last few years, USATT has changed how they handle digital submissions of tournament results.
The first time, they emailed the three people who had tournament software and said the system would be changing in one week (they were going to go live with the change and announce it in literally one week) and they were sure we would be able to modify our apps to support the new formats by then. This was the first we had heard of this, and they didn’t provide any sample data or specs for the new formats.
After several months of discussion with them, I did manage to get them to tell us (decide) what the new format would be and modify Zermelo to work with their new setup. Then a year later, they changed it again and again did not coordinate with us.
Under this new ITTF ranking system, the ranking is not reflective of a player’s playing level and in the meantime, they made head-to-head records unavailable. Many fans will access Rating Central for this information.
Now, you understand how hard to develop the correct rating system. David J. Marcus has spent a lot of time to develop his system. In return, he gains nothing from the association. Now, you know where to find the most accurate rating system for table tennis.
- Marcus, D. J. (2001) New Table-Tennis Rating System. Journal of the Royal Statistical Society: Series D (The Statistician), 50: 191–208. doi: 10.1111/1467-9884.00271
- Marcus, D. J. (2011a) Ratings Central: Accurate, Automated, Bayesian Table Tennis Ratings for Clubs, Leagues, Tournaments, and Organizations. Joint Statistical Meetings, July 30–August 4, 2011.
- Marcus, D. J. (2011b) Ratings Central: Accurate, Automated, Bayesian Table Tennis Ratings for Clubs, Leagues, Tournaments, and Organizations. NESSIS (New England Symposium on Statistics in Sports), September 24, 2011.