Category Archives: 2012

Tokyo Grand Slam Metrics.

As per previous posts, I have been working on a project to collect data from the IJF scoreboards and store them in a database for later study. In this article I want to share some information I have gained from the 2012 Tokyo Grand Slam.


In the last article we looked at day one, in this article we will look at the entire event and discuss a couple of points that come up.


How much actually happens at a Grand Slam?

The 2012 Tokyo Grand Slam was a three day event, spread across 3 mats in the elimination rounds. The semi-finals and finals being held on one mat after a two hour break. In total the scoreboards recorded 1,013 changes to the scoreboards. That includes corrections to scores as we have discussed in earlier articles on this website.

The scoring broke down like this:

  • Minute 1: 111
  • Minute 2: 176
  • Minute 3: 160
  • Minute 4: 160
  • Minute 5: 163


The Ippons broke down like this:

  • Minute 1: 22
  • Minute 2: 27
  • Minute 3: 31
  • Minute 4: 35
  • Minute 5: 45

Out of those 160 Ippon scores, only 6 were in Golden Score with there being a total of 30 scores in golden score time.


A very simple look at the numbers above can suggest that it is in minute 2 you are most likely to be scored against and caught for Ippon most often in the final minute.


As per previous posts, the problem with this basic analysis of the 2012 Tokyo Grand Slam is that the data is never as simple as it looks. The software captures every change to the scoreboard and stores it as a record. So the moment the table official hits the Ippon button the database gains an Ippon. Unfortunately errors happen and when the referee changes the score the database gaisn another record but not losing the original Ippon. This means it is hard to use data in the way shown above, especially for scores lower than ippon that don’t stop the match.


It is good to collect that data however, we could with relative ease determine how many scoring errors were made. A cursory examination for example shows 154 Ippons on the official record, where the captured data shows 160. So Ippon was put on the scoreboards incorrectly 6 times across three days.


We can also look at things like the actual time contests started. The system captures the clock at 5:00 minutes, i.e. the start of the match as the names come on the scorebaord. We can easily collect the timestamps from these records and see for example the distribution of starts across the three days.

  • 11:xx 66
  • 12:xx 72
  • 13:xx 56
  • 14:xx 8
  • 15:xx 0
  • 16:xx 9
  • 17:xx 21
  • 18:xx 11


Contests per hour Tokyo Grand Slam 2012
Contests per hour Tokyo Grand Slam 2012


What we can see is that the competition (across the three days) had the most fights occur between 12 noon and 1pm. This is a 3 mat event, that in the finals section went to a single mat with a break between elimination and finals.

It would be interesting to look at what scores happened in that 12-1 hour. Perhaps there were more Ippons in this period?

This very brief investigation into the data from the event is provided purely to encourage discussion and investigation by others, I know there are real statisticians out there who could dig out interesting information from the numbers. For me this event was mainly about testing the reliability of the data capture and preparing for the next stage where I shall be doing data collection using a Raspberry Pi computer.

I would love to hear your thoughts and opinions.


Tokyo Grand Slam 2012 – Day one.

Today was day one of the Tokyo Grand Slam, one of the final events in the 2012 competition schedule.

Today the light weights took to the tatami and you might expect, the Japanese put on a marvelous display of Judo.

Looking at the data I collected form the IJF scoreboards, Ippon was awarded 36 times, with 23 remaining on the permanent record on
This simple statistic tells us that on 13 occasions the referees awarded Ippon and later adjusted it down to a lesser score. Only 63% of the time did they stick with Ippon after awarding it. Now when looking at this number we have to be careful in reading too much into it and also not considering some of the factors affecting the data.

For example, the 36 number is derived by a simple search for records in the database. The database is populated by a piece of software that waits for a change in the scoreboard and writes one record each time the scores change. So a simple mistaken key press could be an instance here; not just when the referees or commission change a score.

We are also assuming that the 36 and 23 figures are accurate. Both could be wrong, they have not been verified.

Also you need to consider that this is data taken from one day of competition at a specific event. We are at the end of a competition year, post Olympic Games and in Japan. So for example Rishod Sobirov fought up a weight (as is Iliadis Illiadis later in the week). This affects the way people are fighting and the seeding. Obviously Japan has a large team, though it also features younger new players on the scene along with some of their seasoned players.

But this sort of snapshot data is useful, especially if we collect more and more of it over time and are able to grow large reliable sample groups to work with. Today for example the data grew by 296 records, which can be added to the existing data from the few events I have tested the system at to create a set of over 2000 scoreboard actions.

This data could potentially be used for example, to examine when scores are modified most often. The data contains the scoreboard clock data and the actual local time. So we could potentially identify patterns where errors occur. So perhaps (and this is conjecture) corrections happen most at 11:30am, which is perhaps halfway through the elimination rounds. We could use this data to suggest to event organisers a rest period for officials from 11:20 to 11:40 as the data might (again this is purely imaginary) suggest that people are making errors through tiredness.

We could easily discover the nations that score at the start of matches with big scores and those who do so later in matches. We could follow individual players scores over time and see trends in when they score and when they get scored against. Coaches might find this sort of data valuable in their planning.

In summary, collecting this data has proven to be fairly simple and recording it is a database where the information can be analysed is an important next step, one which I hope others will be interested in and maybe after reading this post might contact me with exciting ideas on how the data might be used. If that person is you, then please drop me an email to


Qingdao Judo Grand Prix 2012 data, day two.

Today was the heavier weights here in Qingdao, so when looking at the data perhaps there is a difference in the pattern to that from day one?

Day 2 (-70, -78, +78, -81, -90, -100, +100), Opening Rounds:

Total Scores: 139

Scores in 1st minute: 21
Scores in 2nd minute: 34
Scores in 3rd minute: 34
Scores in 4th minute: 37
Scores in 5th minutes: 13

Ippon scores in 1st minute: 6
Ippon scores in 2nd minute: 6
Ippon scores in 3rd minute: 9
Ippon scores in 4th minute: 10
Ippon scores in 5th minutes: 5

Day 2 (-70, -78, +78, -81, -90, -100, +100), Gold Medal Fights:

Total Scores: 19

Scores in 1st minute: 1
Scores in 2nd minute: 4
Scores in 3rd minute: 4
Scores in 4th minute: 6
Scores in 5th minutes: 4

Ippon scores in 1st minute: 1
Ippon scores in 2nd minute: 0
Ippon scores in 3rd minute: 1
Ippon scores in 4th minute: 2
Ippon scores in 5th minutes: 2


It is also worth noting that the numbers quoted here include all changes to the IJF scoreboards, so includes scores later changed. The minute times mentioned include the golden score as well; so again care must be taken when interpreting the numbers. All this data is included in a database should people be interested in doing some research and analysis.

Of course this is a small sample, but it is interesting none the less to look at the numbers and especially to look at the differences between light and heavy. We need to consider also where we are in the Olympic cycle and how that affects the players attending the event and the level of preparation and focus they might have on the day.

Your comments on this are invited and appreciated.

Preliminary rounds, results:

GP_CHN2012 -100kg Mat:2 2:57 NUNES, Renan (BRA) 100(1)-000(0) DORJ, Anar (MGL)
GP_CHN2012 -100kg Mat:2 2:50 BAUZA, Karolis (LTU) 100(1)-000(0) XU, Xin (CHN)
GP_CHN2012 -81 kg Mat:1 2:04 KHABACHIROV, Murat (RUS) 001(1)-000(1) CHO, Seung Kwon (KOR)
GP_CHN2012 -70 kg Mat:3 0:58 CHEN, Yun-Ting (TPE) 100(0)-000(0) KAUR, Gagandeep (IND)
GP_CHN2012 -100kg Mat:2 2:28 ASANUMA, Takumi (JPN) 000(0)-100(0) XU, Jie (CHN)
GP_CHN2012 -70 kg Mat:3 1:51 MERLI, Nadia (BRA) 000(0)-100(0) OSUMI, Yuka (JPN)
GP_CHN2012 -100kg Mat:2 2:14 MAGOMEDOV, Shamil (RUS) 001(1)-100(2) KIM, Do Hyoung (KOR)
GP_CHN2012 -81 kg Mat:1 0:00 OTGONBAATAR, Uuganbaatar (MGL) 011(0)-000(0) EBI, Yasuhiro (JPN)
GP_CHN2012 -70 kg Mat:3 4:08 VARGAS KOCH, Laura (GER) 110(0)-000(0) CHEN, Rong (CHN)
GP_CHN2012 -81 kg Mat:1 4:24 DAVIS, Thomas (GBR) 100(0)-000(0) GAO, Haiyuan (CHN)
GP_CHN2012 -100kg Mat:2 1:46 CORREA, Luciano (BRA) 100(0)-000(1) ZHAO, Dongming (CHN)
GP_CHN2012 -81 kg Mat:1 3:06 PENALBER, Victor (BRA) 101(0)-000(2) KUMAR, Manoj (IND)
GP_CHN2012 -100kg Mat:2 3:52 KUMAR, Pramod (IND) 000(0)-100(0) KUMASHIRO, Yusuke (JPN)
GP_CHN2012 -70 kg Mat:3 0:00 HAN, Weiyan (CHN) 010(1)-000(3) YOU, Mee Won (KOR)
GP_CHN2012 -81 kg Mat:1 2:23 WU, Wen Shun (TPE) 000(0)-101(0) WANG, Xuewen (CHN)
GP_CHN2012 -100kg Mat:2 3:56 YUAN, Jinling (CHN) 100(0)-000(0) HONG, Yi Chih (TPE)
GP_CHN2012 -81 kg Mat:1 2:42 GAN, Tuvshinjargal (MGL) 101(0)-000(2) TURABOEV, Bekzod (UZB)
GP_CHN2012 -100kg Mat:2 1:14 LIM, Seung Rok (KOR) 000(1)-100(1) HUSSAIN, Shah (PAK)
GP_CHN2012 -78 kg Mat:1 4:01 YANG, Xiuli (CHN) 001(0)-100(0) HIDAKA, Misaki (JPN)
GP_CHN2012 -70 kg Mat:3 0:00 TSEND AYUSH, Naranjargal (MGL) 000(1)-000(0) ZHOU, Chao (CHN)
GP_CHN2012 -90 kg Mat:2 2:25 SINGH, Avtar (IND) 000(1)-100(0) ZHANG, Jun (CHN)
GP_CHN2012 -78 kg Mat:1 1:13 ZHANG, Jie (CHN) 100(0)-000(0) HSU, Hsin-Mei (TPE)
GP_CHN2012 -78 kg Mat:1 4:04 VELENSEK, Anamari (SLO) 100(0)-000(0) CHEN, Ying (CHN)
GP_CHN2012 -78 kg Mat:1 3:15 WANG, Szu-Chu (TPE) 000(0)-100(0) HAN, Li (CHN)
GP_CHN2012 -70 kg Mat:3 0:15 POGACNIK, Anka (SLO) 001(0)-110(1) TAKAHASHI, Rui (JPN)
GP_CHN2012 -90 kg Mat:2 0:00 KIM, Kwang-Ho (KOR) 001(1)-000(2) ZHANG, Zhongbo (CHN)
GP_CHN2012 -81 kg Mat:1 2:18 KHABACHIROV, Murat (RUS) 111(0)-000(0) ZHANG, Wentao (CHN)
GP_CHN2012 -100kg Mat:2 1:43 NUNES, Renan (BRA) 100(1)-000(0) BAUZA, Karolis (LTU)
GP_CHN2012 +100kg Mat:3 0:30 ULZIIBAYAR, Duurenbayar (MGL) 000(0)-100(0) WANG, Quanchao (CHN)
GP_CHN2012 +78 kg Mat:3 5:00 QIN, Qian (CHN) 100(0)-000(0) WOO, Jung-Min (KOR)
GP_CHN2012 -100kg Mat:2 1:53 XU, Jie (CHN) 000(2)-101(0) KIM, Do Hyoung (KOR)
GP_CHN2012 -81 kg Mat:1 1:35 OTGONBAATAR, Uuganbaatar (MGL) 001(0)-000(2) DAVIS, Thomas (GBR)
GP_CHN2012 +78 kg Mat:3 0:00 WANG, Rui (CHN) 002(1)-000(0) ICHIHASHI, Suzuka (JPN)
GP_CHN2012 -81 kg Mat:1 0:00 PENALBER, Victor (BRA) 001(0)-000(2) WANG, Xuewen (CHN)
GP_CHN2012 -100kg Mat:2 0:00 CORREA, Luciano (BRA) 000(2)-001(0) KUMASHIRO, Yusuke (JPN)
GP_CHN2012 +78 kg Mat:3 0:00 ALTHEMAN, Maria Suelen (BRA) 000(2)-002(0) LI, Yang (CHN)
GP_CHN2012 -100kg Mat:2 2:43 YUAN, Jinling (CHN) 101(0)-000(0) HUSSAIN, Shah (PAK)
GP_CHN2012 -81 kg Mat:1 1:57 GAN, Tuvshinjargal (MGL) 001(1)-100(2) LI, Maojian (CHN)
GP_CHN2012 -70 kg Mat:3 1:52 PORTELA, Maria (BRA) 100(0)-000(1) CHEN, Yun-Ting (TPE)
GP_CHN2012 -90 kg Mat:2 3:49 SULEMIN, Grigorii (RUS) 002(4)-100(0) ZHANG, Jun (CHN)
GP_CHN2012 -90 kg Mat:2 0:54 LI, Kunpeng (CHN) 000(0)-101(0) HUH, Chae Goo (KOR)
GP_CHN2012 -78 kg Mat:1 0:00 HIDAKA, Misaki (JPN) 001(0)-000(2) CHOI, Mi-Young (KOR)
GP_CHN2012 -70 kg Mat:3 0:00 OSUMI, Yuka (JPN) 000(1)-100(1) VARGAS KOCH, Laura (GER)
GP_CHN2012 -90 kg Mat:2 0:00 KIM, Kwang-Ho (KOR) 001(1)-000(2) LKHAGVASUREN, Otgonbaatar (MGL)
GP_CHN2012 -78 kg Mat:1 1:29 JUNG, Da Woon (KOR) 010(1)-000(1) ZHANG, Jie (CHN)
GP_CHN2012 -78 kg Mat:1 4:44 VELENSEK, Anamari (SLO) 100(0)-000(0) CHONGTHAM, Jina Devi (IND)
GP_CHN2012 -70 kg Mat:3 0:54 CHEN, Fei (CHN) 001(1)-000(2) HAN, Weiyan (CHN)
GP_CHN2012 -90 kg Mat:2 0:00 CHENG, Xunzhao (CHN) 010(1)-001(0) KITANO, Yuichi (JPN)
GP_CHN2012 -78 kg Mat:1 1:47 POWELL, Natalie (GBR) 010(1)-100(0) HAN, Li (CHN)
GP_CHN2012 -70 kg Mat:3 3:15 ZHOU, Chao (CHN) 100(0)-000(0) TAKAHASHI, Rui (JPN)
GP_CHN2012 +100kg Mat:3 1:42 PASKEVICIUS, Marius (LTU) 100(0)-000(0) WANG, Zhen (CHN)
GP_CHN2012 +100kg Mat:3 4:08 WANG, Quanchao (CHN) 100(0)-000(0) LEE, Po Yen (TPE)
GP_CHN2012 +100kg Mat:3 0:00 SAIDOV, Renat (RUS) 001(1)-000(2) SHEN, Zhuhong (CHN)
GP_CHN2012 +100kg Mat:3 1:05 KIM, Soo-Whan (KOR) 000(2)-001(1) WANG, Qiang (CHN)


GP_CHN2012 -81 kg Mat:2 0:46 KHABACHIROV, Murat (RUS) 001(0)-000(1) OTGONBAATAR, Uuganbaatar (MGL)
GP_CHN2012 -81 kg Mat:2 2:00 PENALBER, Victor (BRA) 100(0)-000(0) LI, Maojian (CHN)
GP_CHN2012 -70 kg Mat:2 2:29 PORTELA, Maria (BRA) 002(0)-001(0) VARGAS KOCH, Laura (GER)
GP_CHN2012 -70 kg Mat:2 0:00 CHEN, Fei (CHN) 010(1)-000(3) ZHOU, Chao (CHN)
GP_CHN2012 -90 kg Mat:2 0:00 ZHANG, Jun (CHN) 001(0)-000(1) HUH, Chae Goo (KOR)
GP_CHN2012 -90 kg Mat:2 2:36 KIM, Kwang-Ho (KOR) 000(0)-100(1) CHENG, Xunzhao (CHN)
GP_CHN2012 -78 kg Mat:2 0:51 HIDAKA, Misaki (JPN) 000(2)-001(0) JUNG, Da Woon (KOR)
GP_CHN2012 -78 kg Mat:2 4:24 VELENSEK, Anamari (SLO) 100(0)-000(0) HAN, Li (CHN)
GP_CHN2012 -100kg Mat:2 0:00 NUNES, Renan (BRA) 002(0)-001(1) KIM, Do Hyoung (KOR)
GP_CHN2012 -100kg Mat:2 0:00 KUMASHIRO, Yusuke (JPN) 001(1)-000(0) YUAN, Jinling (CHN)
GP_CHN2012 +78 kg Mat:2 2:54 QIN, Qian (CHN) 101(0)-000(0) WANG, Rui (CHN)
GP_CHN2012 +78 kg Mat:2 0:00 LI, Yang (CHN) 000(2)-001(1) YU, Song (CHN)
GP_CHN2012 +100kg Mat:2 2:09 PASKEVICIUS, Marius (LTU) 110(0)-000(1) WANG, Quanchao (CHN)
GP_CHN2012 +100kg Mat:2 0:00 SAIDOV, Renat (RUS) 010(2)-001(3) WANG, Qiang (CHN)

Gold Medal Fights:

GP_CHN2012 -81 kg Mat:2 2:43 KHABACHIROV, Murat (RUS) 000(0)-100(0) PENALBER, Victor (BRA)
GP_CHN2012 -70 kg Mat:2 1:59 PORTELA, Maria (BRA) 000(1)-100(1) CHEN, Fei (CHN)
GP_CHN2012 -90 kg Mat:2 1:27 ZHANG, Jun (CHN) 000(1)-100(1) CHENG, Xunzhao (CHN)
GP_CHN2012 -78 kg Mat:2 0:00 JUNG, Da Woon (KOR) 000(2)-102(0) VELENSEK, Anamari (SLO)
GP_CHN2012 -100kg Mat:2 4:41 NUNES, Renan (BRA) 000(0)-100(0) KUMASHIRO, Yusuke (JPN)
GP_CHN2012 +78 kg Mat:2 0:00 QIN, Qian (CHN) 000(1)-000(1) YU, Song (CHN)
GP_CHN2012 +100kg Mat:2 0:04 PASKEVICIUS, Marius (LTU) 110(2)-001(1) SAIDOV, Renat (RUS)




Qingdao Grand Prix 2012 data, day one.

In this article are some simple statistics gathered at the 2-12 Qingdao Judo Grand Prix.

Day 1 (-48, -52, -57, -63, -60, -66, -73), Opening Rounds:

Total Scores: 227

Scores in 1st minute: 43
Scores in 2nd minute: 45
Scores in 3rd minute: 57
Scores in 4th minute: 48
Scores in 5th minutes: 34

Ippon scores in 1st minute: 11
Ippon scores in 2nd minute: 7
Ippon scores in 3rd minute: 11
Ippon scores in 4th minute: 13
Ippon scores in 5th minutes: 6

Day 1 (-48, -52, -57, -63, -60, -66, -73), Gold Medal Fights:

Total Scores: 36

Scores in 1st minute: 3
Scores in 2nd minute: 7
Scores in 3rd minute: 13
Scores in 4th minute: 5
Scores in 5th minutes: 1

Ippon scores in 1st minute: 1
Ippon scores in 2nd minute: 2
Ippon scores in 3rd minute: 4
Ippon scores in 4th minute: 1
Ippon scores in 5th minutes: 0

The data here includes all scores on the IJF scoreboards, including those later changed which is important to consider. Tomorrow are the heavier weights, so it will be interesting to see if the distribution is similar or not.


When do people score in Judo?

Below is a screen shot that shows some very basic information on the heavyweight divisions at the 2012 European Junior (under 20 years) Championships, held recently in Porec, Croatia.

EC_JUN2012 Scores


As you can see, the under 20 championships duration is 4 minutes. The least amount of scoring happens in the first minute, the most in the second minute of the match.

The number of Ippon throws varies minute by minute also. With the last minute of the match being an area of interest. There is proportionately more Ippon scores during the final minute than any other period in the match. The reasons for this we do not know. And this is from a single event.

We can also see that there were 512 scores made in this incomplete dataset, of which Ippon made up approximately 22% of the scores.

As with all statistics, the size of the sample set is important. In this case it is extremely small. This is a dataset collected with a new experimental solution and was only used on one day of the event. We need to consider a much larger sample before putting much weight in these figures; I put them here purely to invite discussion.


The +78kg Category and Tong Wen.

On the 7th of May 2010, the qualification period for the Judo event at the London 2012 Olympic Games started. More than 4,000 athletes from 153 countries have been chasing the precious few Olympic qualification places.

On May 7th, I started my research project looking at an alternative athlete ranking system for Judo.

The IJF has a qualification system that has been in use for many years, initially just within the EJU but now for the first time as the method of qualifying for the Olympic Games. The system I have been experimenting with has been running in parallel to the IJF system quietly collecting the match results from the 75 qualification events held so far.

The two systems are different at a fundamental level. The IJF reward points to athletes based on the position they reach in the tournament. My system adds or subtracts points after each match. In the IJF system the points awarded are based on the event and the position you reach. My system awards points based on the calculated probability of a player beating their opponent. The idea being that if you beat the best in the world and come first; it should be worth more than beating weaker players and coming first.

One of the categories I have found very interesting is the +78kg category, in part because I am a fan of British fighter Karina Bryant. It is also the smallest category in elite Judo (only 146 athletes). This means it is comparatively easy to watch the category. Also, this category features the infamous Tong Wen of China. Tong Wen (佟文) did not compete for two years after running into trouble with the banned substance clenbuterol; before being cleared and re-entering competition last year at the 2011 Moscow Grand Slam.

Tong Wen is the reigning Olympic Champion and has 7 world gold medals (according to ). So an athlete of this calibre re entering the category late made it very interesting.

From the perspective of my research it was equally interesting as after her first event, my system had her ranked at (if memory serves) #2 or #3 in the category. Where as the IJF system did not have her in the top ten. The reason being that the IJF system only factored in the points from winning that event. Whereas my system took into consideration the fact she beat KONITZ Franziska, POLAVDER Lucija, KOCATURK Gulsah and KIM Na-Young that day. She has fought a total of 21 times and won each one with Ippon (I am excluding the recent default to team mate QIN Qian at the 2012 IJF Masters  in Almaty. She is (I believe), the only athlete undefeated in the category.

Yet, Tong Wen is not ranked number one under the IJF system, only third, behind TACHIMOTO Megumi (who she beat at the 2011 World Championships) and QIN Qian (who she has beaten three of the three times they have actually fought). As you can probably guess, my system ranks Tong Wen #1 above TACHIMOTO Megumi (#2) and QIN Qian (#3).

I think it is fascinating to compare the systems and this category is proving very interesting to follow.

Once Qualification closes on May 1st 2012, I shall write a report on the project and I would appreciate any and all feedback on the systems and how they compare from whatever perspectives you might have. Be that a player, a coach, a statistician, and administrator or a interested fan.

Please do ask any questions or send your feedback to me at



London2012 Qualification and a comment on typos.

As many know, for the past few years I have conducting research on the ranking of elite level Judo. Specifically, I have been running and experimental ranking system for Olympic qualification using the ELO ranking system and all the IJF ranking events.

To date (not including the 2011 Tokyo Grand Slam which is happening whilst I write this), there have been 17,542 fights in the qualification period. The qualification period started in the 2010 Tunis Grand Prix and there have been 64 events so far with approximately 150 nations and approximately 3,781 athletes all in the mix.

You’ll notice I said “approximately” there. That was intentional. Since the qualification started I have identified over 300 typographical mistakes in the names of athletes reported by the tournaments. Thats approximately 11% of error. Now, my data is sourced from and that technically is not the definitive record. However, it is generated directly from the tournament software used in the stadium, so I can imagine that the errors carry over to the official written records.

The IJF’s own ranking system is I think accurate (at least as far as I can see) this is mainly due to the diligence of the hard working lady who looks after the list. The IJF ranking list is maintained manually and it’s hard to fathom quite how much work goes into maintaining it! I know from my experiences running my experiment ( on by the way), that maintaining accurate information is very hard. I am lucky to have had lots of help from people, not least of all from

In my experimental ranking system for Judo, accuracy is vital. My system awards or deducts ranking points from athletes after every fight. Unlike the IJF ranking system, my system looks at every fight; the IJF look only at the final positions. So the IJF system requires less accuracy arguably, as you need only make sure the final results are right. After all, 50% of the names are gone after the first round at most events so need not be entered into the IJF system. On my system however, those names need to be right.

The reason they need to be rights is that points are awarded based on the predicted chance of player a beating player b in that specific match. As I calculate that chance for each fight, it matters as the ranking points are awarded after each match. Lets say you have a “Joe Bloggs” who wins points in competition A, getting a ranking of perhaps 1580. If they are mistakenly called “Joseph Bloggs” in competition B, then my system thinks they are a new person and there 1580 points are not applied and a new athlete enters the system.

This is bad as I would earn more points at competition B for beating a player with an existing rank of 1580 (Joe Bloggs) than a new athlete (Joseph Bloggs) who would start with 1500 points. In the IJF system, if Ilias Illiadis beat Joe Bloggs in round one it matters not at all if his name is wrong; because who you beat does not matter, only the position you get to. If Joe Bloggs makes it far enough to earn points, then there name being wrong would matter. However, as the IJF system is manual it’s perhaps going to get picked up at that point.

It is thanks to “encouragement” from others that I have put more and more effort into the accuracy of the names. I have about 330 corrections and as it’s automated so it should stay right. Of course, there is another problem which is one I have not yet attacked. What to do about athletes who have the same exact name! It is difficult to find workable solutions to that problem. How do you decide if two names that are identical are not the same person? How do you decide two identical names are not to different people?

As the software I have written matures I hope to find good solutions these sorts of problems. For now I have 330 specific corrections;I have found by manually going through the data and fixing mistakes people point out (please do check and see if you find any mistakes).

My future plans are to publish a final report on the experiment after the London2012 Olympic games, this will go along with the poster presentations I have given at the European and World Judo Championships. I also plan to open source the software and data, so that others can improve on what I have done and take the research further or in different directions. I have already created a data API, so that people that want it can easily obtain machine readable access to my record of the 17,542 fights that make up the qualification race for London2012. If you would like access please let me know.



Lance Wicks.

The International Judo Federation (IJF) Ranking system.

This weekend (25 January 2009), the first of the events of the IJF ranking system will be held. The new system of ranking is important as it shall decide who can attend the London 2012 Olympic Judo tournament. In this post we shall take a good look at the system…

IJF Ranking Points System.
IJF Ranking Points System.

As you can see from the table, athletes are awarded ranking points depending on the position they reach and the event they are competing in.

So, win the World Championships and get 500 points, win one of the new masters events and get 400. Third in my native OJUs and you’ll get 32 points.

Come 30th April 2012, the players ranked in the top 22 for men, or top 14 for women (per category) are the qualifiers for the London Olympics.

The system gets more complicated from here on in, only the top 5 results per year are counted. So if you were to win the 2009 World Cup, Grand Prix, Grand Slam, Masters,World Championships and the OJUs; you would receive 1400 points. However, these points will not actually be worth 1400 in 2012, they will in fact only be worth 350 points as the points “degrade” by 25% per year (The dividing line is the beginning of the month in which the tournament ‘s first
competition day, was held).

Now the rest of the places in the games will be chosen by the Continental unions. Each continental union gets half the number of National Federations affiliated to each that union. So the EJU which has 50 member states and would receive 25 places for athletes who do not make the top 22/14.  These will be decided basically by the top points scorer in the continent, until the fill quota is used, with a maximum of two athletes per category being qualified by this method.

The new system starts with all athletes having zero points. So this weekend is the first opportunity for them to start qualifying for 2012.
It is however based on the result in the tournament not on the athletes you beat. If you happen to have the easiest draw in history at the World Championships it is worth just as much as if you fight all the top athletes in your category. Will this work well is to be decided, I have not seen what research was done in deciding on this system.

Personally, I am more in favour of a system like the ELO system used in Chess (and online gaming like Xbox Live). The ELO system takes into consideration the probabilities involved in one athlete beating another. If a player who is much lower on the ELO ranking beats a higher ranked player, they receive a larger number of ranking points than if they beat someone below them. It is my intention, if I can obtain all the draw sheets, to run the ELO system and monitor the rankings to see if it ranks athletes over the 4 years differently.