Category Archives: Judo

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 Ippon.org 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 http://www.rwjl.net 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 http://www.judoinside.com

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 http://rwjl.net 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.

Regards,

 

Lance Wicks.

An experimental relative skill based ranking system for elite level Judo.

This week I am in Istanbul at the European Judo Union Championships where, along with other things, I am attending the EJU Research Symposium.

I am presenting a poster on the research I have been conducting on a different way of ranking Judo athletes who compete on the world circuit. Below is the poster:

An experimental relative skill based ranking system for elite level Judo

The summary of the research was very clearly summarised by Dr. AnnMaria DeMars on Twitter as being:

“Getting 3rd on a bye & 1 win != beating the current world & European champs to get 3rd”

The system I am experimenting is based on the Elo system that is used in Chess and various other sports. The concept being that we award ranking points to athletes based on who they beat on a match by match basis as opposed to awarding points based on what position in the medal table they reach.

I am really hoping to get some great constructive criticism from the european Judo research community as I hope to present the research at the IAJR Symposium in Paris later this year.

 

Have the new 2010 rules affected Judo?

Nage pointThis past weekend we entered the official qualification period for the London 2012 Olympic games. In this qualification period the new rule changes are in effect (and are not supposed to change) and it is worth taking a brief look to see if the changes are having an effect on the Judo being played. In this post, we shall compare data from the 2009 Moscow Grand Prix and last weekend’s 2010 Tunis Grand Prix.

If you recall, last year we looked at the 2009 Moscow Grand Prix on this blog ( http://judometrics.com/2009/06/moscow-judo-grand-slam-2009-data/ ) using data from www.ippon.org on the scores and penalties awarded in that event. In this post we shall look at the same data, from the same source, from the 2010 Tunis Grand Prix.

In 2009 we found that Ippon made up 77% of the throwing scores in male Judo and 39% of the female throws. In 2010 we find that Ippon makes up 75% of Male throws and 55% of female throwing scores. Thats a decreaqse of 2.40% in men, but a 15.44% increase in Ippon scoring throws in womens Judo.

Within mens Judo we se a 8.10% decrease in Wazari scoring throws and a 10.49% increase in Yuko scoring throws. On the opposite side, womens Judo has decreased the number of Warazi (9.74% decrease) and Yuko (5.70% decrease) throwing scores.

Looking at the number of penalties per match, we see that in 2009 it was 1.61 penalties per match and 1.84 in 2010 for men. The women had 1.39 penalties per match in 2009 and 1.51 penalties per match in 2010. Looking at the scores per match, they have changed very little between 2009 and 2010 (.56->.59 for men, .78->.79 for women). If we look at direct Hansoku Make penalties, unsuprisingly we see the men go from 1 in 2009 to 11 in 2010. The females also increased their Hansoku Make from 0 in 2009 to 2

So to summarise, in men’s Judo we have fewer Ippon and more penalties. Women’s Judo on the otherhand has more Ippon throws and more penalties. BOth men and women have an increase in Hansoku Make, which we can presumably associate with the new leg grab rule.

This very brief look at the data gives only a snapshot of elite Judo from two events; two events in Europe. So we can’t and shouldn’t read too much into the numbers. This data does not look at the style of Judo on display. It is perfectly possible that the Judo shown in 2010 is more exciting and “pure Judo”.

However, these numbers do provide a view of Judo that we need to consider. My understanding was that the rule changes were devised to increase/promote throwing Judo. “Pure Judo” as it was phrased. My interpretation is that this has arguably been the case in Women’s Judo a 15.44% increase in the Ippon statistic is very positive.  But the general trend towards even more penalties is a negative; this might be a result of the rule changes, or different fighting styles; we can’t tell from this examination.

If we look broadly, the number of scores per match has increased in both men and women, as has  the number of scores from throws; from 1.61 to 1.86 per match for men and 1.67 to 1.86 per match for women. However, the number of scores per match from throws has only increased from .56 to .59 for men and .78 to .79 for women.

More investigation is required, an investigation into the style of Judo displayed would be interesting; as would a long-term study of the objective data over a wide range of events.

How do you feel the Judo from 2009 and 2010 has changed? How do you feel the rule changes have affected Judo? How do you think we can further explore the area?

The ages of Olympic Grapplers (Judo and Freestyle Wrestling).

www.army.milIn this article we look at the ages of Judo athletes and of Freestyle Wrestlers at the Olympic level, this follows on from the article back in March (2009) on the “Ages of medalists at 2009 Judo World Cup events.” in which the age of Judo athletes competing at a high level was briefly examined.  In this article we look at ages of athletes in more detail and compare Judo against our Olympic cousins Freestyle Wrestlers.

In March the average age of a medalist was identified as being 24.95, looking at the larger pool of athletes in the 2008, 2004, 2000 and 1996 Olympic games the average age of a medalist in Judo is 25.54 for men and 24.99 for women.

Judo Gold medalists are on average 25.07. The other Judo medalists are on average 25.27. If we compare this to Freestyle Wrestling where the average age of athletes is 25.41 and gold medalists are on average 23.83 years of age.

What does this tell us?

One interpretation of this information is that grapplers at the Olympic level are in their mid twenties.

If we believe the theory that it takes 10 years to reach the elite level (as popularized by Malcom Gladwell’s Outliers book – UK/US) then we need to start working with young Judo athletes of 14/15 years. Obviously a 14 year old is not (normally) fully mature physically, so a long-term strategy needs to be implemented to bring the young athlete to the Olympic stage.

Having said that, if we look at the average age of Judo athletes over the 4 Olympic (1996-2008), we see the average age has actually crept up over this time from 24.96 to 26.14 years. The gap between gold and the average has changed too, from about three months in 1996 to 1 year in 2008. So perhaps the best players (the gold medalists) is not going up as fast as for the rest of the players? A simple examination does not make this clear, especially as the sample size of gold medalists is of course much smaller than the general population.

This is a small example of the sort of information this data can tell us. If you are a national governing body, do you invest your limited resources in athletes who will be outside of their mid-twenties? Do you target 14 year old athletes? This data can’t answer those questions, but with better research perhaps you could find the objective information to help make decisions in this area?

I shall look at the data in more detail but perhaps you’d rather do it for yourself?
I have uploaded my raw data at http://spreadsheets.google.com/ccc?key=0AqIP2spU5FrFdFR5UFdTUzdmaHVfc0FvUzZpLUR4YXc&hl=en

This  simple examination of Judo data is an example of the type of activities coaches on the EJU coaching certification courses do. It is also an examination of the type that can lead to more through research which could lead you to the International Association of Researchers.

—-

Data was collected from http://www.sports-reference.com/olympics

A case for experience… Athletes who competed in 2005 and 2007 World Judo Championships.

Within the Judo coaching community we often argue about the value of experience, about the value of attending the “big” events even if you don’t win. So this week I decided to look at the athletes who competed in the 2005 World Judo Championships in Cairo and also in the 2007 World Championships in Rio de Janeiro. It is a simple look at the -81kg category across a mere two events, so it is only a very basic examination. The results are of interest and it would be worth researching properly.

Of the 58 athletes who fought in the -81kg category in Cairo, 21 (36%) returned to the -81kg category in 2007.

Looking at the top 8 players, 3 (37.5%) returned to the category in 2007; including the Gold and one of the Bronze medalists.

Seeding:

By examining the seeding position for the 21 athletes we see that 14 (66.6%) of the returning athletes came back seeded higher than in 2005.

Position in tournament:

Of the 21 returning athletes, 15 (71%) reached a later round of the competition in 2007 than they did in 2005. Three (21%) athletes reached the same point in the event and four (19%) did worse in 2007 than in 2005.

What does this suggest?

Obviously, very little examination has been done. The point of this article is only to start a train of thought, not to prove a hypothesis, so please take the following as ideas only, not scientific proof.

What the information suggests to me that there is some truth to the idea that attending the World Champs is a sensible decision in the long term planning of a Judo athlete. It suggests to me that you need to go to the world champs more than once and that your performance should improve at the next appearance. From this data we see this is right 71% of the time.

It is perhaps interesting to consider your athletes position in the world order, what if for example they lose in the first round? Well looking at the 6 athletes (from the returning athletes) that went out in the first round in Cairo, only one failed to improve upon this in Rio. 3 made it to the second round, 2 made it to the 3rd round and 1 made it to the 4th round. So perhaps sending inexperienced players who lose in the first round is not pointless as some suggest. Especially as those who made 2nd round in 2005 also tended to improve, as did those who made the third round.

Further Research:

For performance directors and national coaches making hard decisions about who to send to the World Championships, then more research might help determine an evidence based reason for sending or not sending athletes. It would be interesting to repeat this simple examination across all the categories and see if the results remain similar. Also another extension to this would be to look across earlier World Championships.

I would very much like to know for example how many World Championships athletes attend on average. How they improve across events; can an athlete go from losing in the first round to winning the event over a number of events? Or, is there a minimum level you need to make on your first appearance to get a medal in a later event? Do nationalities affect these figures?

If we are able to identify a consistent progression, can we manage our performance/medal target “pipeline” by looking at what we get today?

Tre Torri Judo Tournament Corridonia – 2009 B-Tournament – Porto Sant’Elpidio, Italy (ITA)

In this post we shall use the JudoInside.com website again to explore a Judo competition and the data we are able to obtain from this freely available source. Today we shall look at the Tre Torri Tournament held recently in Italy, the event is a B tournament and was well attended and this event was choosen to look at as the British Team attended including many of it’s 2008 Beijing Olympic players.

We shall look at the men’s categories, not for any other reason than to save time, we shall not look at the female categories. Using JudoInside.com we are able to collect some data on the percentage of fights each athlete has won on an annual basis. This is data available on the JudoInside.com website on June 18th 2009, so is limited by the completeness of the information available on that site. There are some obvious anomalies  in the data, but for the purposes of this post we will just accept them.

So lets look at the raw data:

Raw data from Tre Torri Judo TOurnament 2009

From left to right what this data shows is the number of fights JudoInside.com had recorded in the “Head to Head” statistic (including fights prior to 199). This is followed by the athletes name and then by the past decade of results. The results consist of a percentage of fights won by the player according to the website. The final column is an average of all the percentages from 1999-2009. Below the main table is a summary of the average percentage for each of the medalist types and also the number of fights recorded for each medal type.

The summary information shows immediately an interesting statistic, the winners of the categories had many more fights on the system than the players they beat, and this was consistent between second and third place winners also. This might be used to support a hypothesis that Judo success requires a certain level of competition experience. That without having competed in enough events you will not win.

This is only one data point and should not be looked at in isolation.
We need to consider the level of this competition, it is a B tournament, not an elite level competition, yet we have players like former World Champion Craig Fallon, Olympian Eaun Burton and of course Tamerlan Tmenov. The long contest record of Tamerlan Tmenov for example affects the averages. Francesco Bruyere and Tamerlan Tmenov are the only two players to have a record in each year for the full decade.

So lets chart the data above:

Chart of winning percentages across past decade at Tre Torri 2009

This is a bit messy, but if you look carefully you can see some interesting information about the athletes. For example, the density is clearly higher in the last 4 years, perhaps indicating the length of careers of players in this event. Comparatively few athletes have careers extending over more than 4 or 5 years. This information might support a hypothesis that there is a optimum length of career, which might become part of a long term athlete development plan if proven. If we were to simplify the chart or chart each athlete separate out athletes you might be able to determine trends in victory percentages, which could be used to assess if an athlete is progressing well or slipping perhaps.

After doing some simple analysis like this in a spreadsheet, it might be interesting to look at a variety of charts and see if anything comes to eye. A simple way to do this is to import the data into Swivel and let it’s automated system create some visually pleasing charts for us. And we can easily see for example the following summary of 2008:

2008 by Athlete

Where we see that no athlete had an unbeaten year, and that the Italian player Giovanni Di Cristo was statistically at least, the best player in the bunch. We can also see pretty clearly in this next chart (below) which players are the most experienced.

Total Fights by Athlete

This is just a quick summary of the event and yet it gives some insights that might be relevant to a coach of B Tournament level players, or even of an elite level coach looking to learn more about the players in the level below him and how they progress upwards (and in this case downwards). It could be interesting to researchers looking to discover more about our sport.

The data is available on Swivel, so please do take a look and leave a comment on this site telling me what you discover or find interesting.

Moscow Judo Grand Slam 2009 data.

In this post I want to look briefly at the statistics from the Moscow Judo Grand Slam 2009. I am going to base it on the information gained from the great website www.ippon.org developed by Matthias Fischer. Ippon.org nicely summarises the information from events and gives some descriptive statistics for us to browse and interpret.

Number of Scores per Judo match:
The first area we shall look at is the number of scores per match. We can look at this and see that there is an average of 1.65 scores per Judo fight. Men averaged 1.63 scores per fight and women averaged 1.67 scores per fight.

Number of Ippon scores awarded:
This seems easy to identify, but is in fact slightly more complicated than the figures might initially suggest. Looking at the men’s categories half the scores are Ippon; however this includes penalty scores so rather than 90 Ippons, this means there are in fact only 77 Ippon throws in the men’s and 39 Ippon throws in the Women’s categories. That means only an average of approximately 36% of scores are from Ippon throws across the categories.

If we extend this we can remove the Shido from all the other scores also. This gives us for the men 77 Ippon Throws, 20 Wazari throws, 3 Yuko throws and no Koka throws with the new rules of course. This conveniently comes to a total of 100 throws, so we can see in the men 77% of throwing scores are Ippon. Which is great except that if we include penalties, Ippon throws are only 27% of the total scores, Penalties make up 65% percent of the scoring!

In the women there were almost the same number of throws (99), but the distribution is quite different. 39 Ippon Throws, 32 Wazari and 28 Yuko. There is quite a difference also in the penalty percentage in the Women’s categories, Penalties make up only 44% of the scores.

It would be interesting to examine the video footage and try and determine structure of men’s and women’s Judo at this event is quite so different. Perhaps it can be stylistic differences between nations and the sexes?

This is just a simple examination of the data but shows perhaps a little of what we can determine from the data generated by www.Ippon.org it is a site you should definitely checkout and keep an eye on.

Any comments or questions would be appreciated,

Lance

The Metrics of the Rules of Judo

IJF Rules Wordle
Image From Wordle.net

Judo, like any sport is subject to rules that define the sport and what is and is not acceptable, the rules are the skeleton that the sport builds around. The rules of Judo are relatively simple when compared to some other sports. The sport closest to my heart is Rugby Union which has 196 (or 77 if you cut and paste just the words) pages of rules (admittedly spaciously formatted) compared to Judo’s 29 pages.

The image above shows the focus of the IJF rules based on word density, which can give us an indication perhaps of the importance each of these words has on the sport of Judo. It is good to see that “contestant” and “contestants” are right up there with “Referee”. This places the player(s) the number one priority in the 13,000 (approx) words that make up the Judo rules. So lets look at Rugby Union and see how their notoriously complicated rules stack up against Judo.

IRB Rules
Wordle of the IRB Rules.

You can quickly see that “Player” and “Ball” standout in the (approximately) 39,000 words that make up the IRB Rugby Union rules. What perhaps is interesting is the prominence of the word “Penalty” in the rugby union rules compared to Judo. In our wordle it is difficult to find Penalty (it is visible) or Shido. Does this suggest that penalties are a bigger part of the game of Rugby than the game of Judo? Also interesting is the prominence of the word “referee” in both images, Referee is more prominent in Judo than Rugby, does this suggest that in our rules the Referee is a bigger factor?

Two other interesting words to consider is the word “Area” in Judo, does this suggest that much of the rules of Judo are about the contest area? In Rugby, the word “Scrum” stands out, which is not surprising given the rule changes made to protect the players from serious injuries in that part of the game.

Another look at this data shows us the top five words in the IJF rule book:

IJF Tules Top 5 WordsThis table shows us again the importance of the word Referee and adds to our investigation by showing the distribution of the top 5 words throughout the rule book.

As one might expect, the word referee is more wide spread throughout the rules whilst contestant for example is more focussed in one area.

You might also suggest from this table that the use of the words contestant and area do not coincide very often, suggesting that these items are very seperate within the rules of Judo.

If we look a little more deeply we can see the following:

Total words: 13080
Unique words: 1577
Words that occur once: 654
Words that occur twice: 245
Highest word frequency: 1380
Average words frequency: 8.29

List top 10 words not in the stop word list

Word: Count

referee: 177
contest: 171
contestant: 158
shall 142:
area: 129
contestants: 103
article: 101
judges: 63
competition: 62
position: 55

If we merge “referee” and “judges”, they total 240 occurances and if we merge “contestant” and “contestants”, which comes to 261 occurances. Players (contestants) come in higher than referees, but only by a small margin. From this the  words “position” and and “area” both are of interest due to their relevance in awarding of penalties, calling of Matte etc. What is interesting here is that Shido and Matte do not occur often enough to rank in the top ten words. Susprising perhaps, given the amount of Matte and Shido calls by referees observed in modern Judo.

The obvious next step(s) is to analyse the use of these keywords in the text and draw some conclusions. This is of course beyond the scope of what we want to look at in this article, so lets examine words that matter to players perhaps? So lets look at “Shido”, which is you have been following this site for a while or observe much Judo contest you will know is a major factor in modern Judo in terms of scores, strategy and so forth.

This suggests to us that the word “shido” is being used primarily in relation to a contestant, nothing too exciting there.

The Word Shido only occurs 8 times within the rules of Judo, however we know from observation that Shido occurs frequently within a contest, so these rules are ones that perhaps all players, coaches, referees should learn thoroughly?

It is interesting that a word that only occurs 8 times (out of almost 13,000 words) accounts for around half the scores in Jud(at least according to the research of people like Sikorski et al. (1987) and my own research of the Beijing 2008 Olympic Judo).

So What about Ippon?

Summary: 32 entries found.


End of Contest 20 . Ippon 21 . Waza-ari awasete Ippon
Ippon 21 . Waza-ari awasete Ippon 22 . Sogo-Gachi 23 .
the following actions : i Ippon : shall raise one arm
to shoulder height . iii Waza-ari-awasete-ippon : First waza-ari , then
: First waza-ari , then ippon gesture . iv Yuko :
Article 13 – Osaekomi time Ippon : total of 25 seconds
shall be extended until either ippon or equivalence is announced or
shall be extended until either ippon is scored or the referee
a When one contestant scores ippon or waza-ari-awasete-ippon Articles 20 and
one contestant scores ippon or waza-ari-awasete-ippon Articles 20 and 21 .
Where one contestant has scored ippon or equivalent , he shall
case where both contestants score ippon or sogo-gachi simultaneously the referee
has been no score of ippon or equivalent , the winner
result . Article 20 – Ippon The referee shall announce ippon
Ippon The referee shall announce ippon when in his opinion an
declared the winner . Simultaneous ippon See Article 19 f
. Appendix Article 20 – Ippon Simultaneous techniques : when
. Should the referee announce Ippon during ne-waza in error and
avoided the necessary criteria for ippon , the referee may nonetheless
the referee may nonetheless award ippon or any other score he
authorise the referees to award ippon when the effect of a
altogether . Article 21 – Waza-Ari-awasete-ippon Should one contestant gain a
referee shall announce waza-ari awasete ippon . Appendix Article 21 –
. Appendix Article 21 – Waza-Ari-awasete-ippon Article 22 – Sogo-gachi compound
the four elements necessary for ippon see Article 20 a and
Waza-ari Although the criteria for ippon of largely on the
other three elements necessary for ippon : Examples : i Partially
continue until the announcement of ippon or waza-ari or equivalent in
equivalent in the case of waza-ari-awasete-ippon or toketa or matte .
Sweeping hip throw Hiki-wake Draw Ippon Full point Joseki Head table
An arm-lock technique Waza-ari Almost Ippon Waza-ari-Awasete Two waza-ari score Ippon
Ippon Waza-ari-Awasete Two waza-ari score Ippon Yoshi Continue Yuko Almost waza-ari

Ippon occurs 32 times, 4 times more often than Shido, yet Shido is a much more prevalent score in Judo, what does this suggest about the rules?

This is a very basic example investigation of the rules of Judo, mainly to serve as a demonstartion that it is possible and how we might approach analysis of the rules beyond looking purely at the rules in terms of action on the match. The question is can analysis of the rules as a text document provide insights into Judo that can have a positive efeect on the sport?

Perhaps you have more time (and experience) at examining text and might be able to find some interesting findings in the IJF rule book. Please let me know if you do.

Lance

Attack rates in Judo.

The following post is another summary of the work done by Dave Elmore of Wolverhampton University, who is a colleague of mine on the University of Bath Foundation degree. This piece of research was done as part of the Bath course and Dave has kindly allowed me to share it here. For those not aware of the course at Bath, it is a fantastic learning opportunity for any person dedicated to Judo. It covers everything from the Origins and HIstory of Judo to the latest scientific research and modern Judo waza, not to forget Kata also. Applications for the 2010 intake are open now, so please do visit the website and consider signing up.

Scores at 2008 Prague Judo World Cup

What the chart above shows us very simply is when scores were achieved in matches at this event, broken into 30 second segments. This chart is based on the toal number of score across categories. You can see that during the 21-90 second mark the number of scores is reaches a peak, then drops off; followed by another peak at 271-330 seconds.

This data can be interpretted in a number of ways as players, coaches, physiologists and analysts. Tactically, we can look at this and suggest that our training programmes need to prepare our Judo athletes to expect higher work rates at these two peaks. Strength and Conditioning be it in the gym or in the Dojo could be modelled around the structure shown in the chart.

Of course there is more to the story than this, we need to look deeper before making radical changes to our training regimes.
For example, we need to look at the weight category that your Judo athletes are competing in, below are chart is from the -60kg and +100kg categories, does it tell a different story?

Scores Vs. Time 2008 Prague Judo World Cup

The above chart shows some differences between weight categories that are interesting. The +100kg category shows a marked drop off in scoring after the peak at 151-180 seconds. The -60kg players appear to show a more consistent scoring pattern across the duration of the matches. This may be purely due to the physical characteristics of the players in these weights, we do not know.

Both the charts above include all scores in the matches, which is interesting but argueably less interesting that when the decisive, winning score occurs in a match. Luckily, we have this information too.

Winning Scores vs. Time

The chart above suggests that there is a period of risk after around one minute, around three minutes and finally near the end of the match. The numbers of scores in these “hot spots” increases as the match goes on. The “dips” may indicate periods where players are resting? Perhaps we can train players to attack in the dips, where the majority of players are not scoring? This is one perspective of the data at least. Again this is data covering all attacks and all categories, lets look more closely at the data for individual categories.

Judo -60kg winning scoresThis chart shows when the scores that won the matches occured in the -60kg category of the 2008 Prague World Cup. From this we can infer that the period from 211 seconds through 300 seconds is the “hotspot” at which point you are at the greatest risk of being scored against (or of course you have the greatest opportunity for scoring). Players can be trained (potentially) using methods that capitalise on this identified “hotspot”.

Here, for the first time we also see shat scores are occurring when. Shido is sadly the most common score. Let us now look at a entirely new category, the -81kg category.

picture-4This chart of the -81kg category of the 2008 Prague World Cup shows a very different shape to matches. Here there appears to be a steady increase in scoring up to the 181-210 mark, at which there is a sharp decline. There are a variety of ways this information might be used; perhaps if your athletes can be trained to withstand the onslaught leading up to the 211 seconds mark they might profit from planning their own barrage later in the match?

What is also interesting in this category is the large gap between Shido and Ippon scores and Wazari, Yuko and Koka scores. There is also what looks like a clear relationship between the Ippon and Shido scores, the peaks are consistently at the same places. What does this suggest? Why is there a difference between this category and the -60 fighters?

Perhaps at this point it is worth considering the overall scoring rate again, but look at the individual scores rather than an amalgamated chart:

Scores vs. Time

This chart shows some interesting data that might be of interest. For example, the jump in Shido scores at 271-300 might show the penalties that accrue as a player ahead on points defends their lead at the end of a match. It is also clear that Shido is the top socre in this event, followed by Ippon, Wazari, Yuko and lastly Koka.

Perhaps it is data like this that served as proof to the IJF to scrap the Koka in international competition, seeing as it is clearly the least frequest score. Perhaps now that Yuko incorporates (some) Koka a future investigation might have Yuko more frequent than Wazari?

In terms of player preparation, can we apply what the data shows us? Should we be teaching/training Koka Judo? Is it an effective use of training time? Even at the “golden score” (301-420) stage of the fight Koka is infrequent. Should more time be dedicated in training to preventing or generating Shido?

The data from this study is fascinating, and it is interesting to consider the implications it might have in modern Judo preparation and competitive tactics and strategy. This sort of study and our own analysis of it in terms of our own specific situations may highlight potential changes in training or performance Judo that we can implement.

To close, I would like to thank Dave Elmore once more for sharing the data he collected with me and allowing me to share it online. Dave is doing great work which is not only statistical in nature. here in the UK he is perhaps better known for his work in the Advanced Aprenticeship In Sporting Excellence JUDO (and blog). If anyone is interested in enrolling for this course in September 2009 here is a document which gives more information and contact info: what-is-aase-word-doc.

Lance.

An examination of BJA Dan grades (Part 2)

In this the second part of our examination of the British Judo Association (BJA) Dan grade register we shall look at the dates grades were awarded.

Dan grades awarded from 1960 to 2008

In this chart we see the number of dan grades awarded per year of all levels between 1960 and 2008. You will see there is a sudden jump in the early 1970s, followed by a steady growth (with peaks) ever since.

From the data we are not able to determine the reason for the sudden jump, common sense suggests that this has more to do with recording of data rather than actual changes in the grading structure.

The average (mean) number of Dan grades awarded per year is 237.16 (+/- 125.98).

The Average Growth year on year is 7.4 (+/-  49.24).

It is perhaps interesting that there is a visible increase in the number of Dan grades being awarded, when the “old wives tale” is that Judo is on the decline.

In this second chart we can see which months the Dan grades were awarded, which shows us that March, June and November are when a majority of grades are awarded.

This perhaps suggests the times of regular gradings. January and December we would expect to be less due to the Christmas season. What is surprising is that August is the month with the least grades awarded, it is summer, but personally I would have expected December and January to be lower. perhaps quite a few people grade just prior to the end of the year and after a Christmas break?

Of course, as mentioned in part one of this examination, this data is not complete. One big weakness is that we do not have a record of prior gradings, just the most recent. The data presented is a “snapshot” only of the BJA Dan grade register as of late March 2009.