An examination of BJA Dan Grades (part one).

So far, a majority of the information shared on this site has been about performance Judo and the metrics associated with competition Judo. This is, of course, just a subset of the Judo world, so this article is not about elite performance Judo rather about the demographics of a Judo association.

Future Black Belt
Picture by MikeOliveri

The British Judo Association (BJA) maintains a record of all Dan grades (Black belts and above) within their orgainsation. They also make this  information partially available via their website at http://britishjudo.org.uk/technical/grading_dan_register.php which means that I was able to peruse that data and make some basic analysis.

Before we begin, we should consider that the website of the BJA is not kept up to date, the Dan grade register should not be considered accurate. Also, the information is not made available in a easy to access format, you can reach only one record at a time. So to conduct any analysis of the information the first step was to scrape the BJA website and pull the data into a MySQL database where queries could be run. The data scraping process can introduce errors into the information.
Finally, the register provides no information on past grades or if the people listed are alive, deceased, members or retired. There are anomalies in the data such as the total number of entries in the database not equalling the number of grades at each level, this is caused by inconsistencies/errors in the data. This data was collected on March 26th 2009.

Simple descriptive statistics about the BJA dan grade register.

Male Dan Grades:        9941 (84.22%)
Female Dan Grades:        1862 (15.78%)

If we focus on female Dan grades, we can compare this to the general population of the BJA by referring to the BJA 2007/08 Annual Report.

A quick analysis of this data shows the following:

Male:        20226 (75.56%)
Female    :      6541 (24.44%)

Now if we compare these two basic percentages, we see right away that despite women being approximately a quarter of the Judo population, less than 16% are Dan grades. We do not have enough information to make any inferences as to why this is, but we can suggest there is an issue here that needs addressing by the BJA. Why is their an imbalance between male and female when compared to the wider Judo population. Is it a case of institutional sexism, or are there other forces at work, like for example maternity.

The general population also includes children, so we should not read too much into this difference in percentages. However, it does perhaps suggest that the BJA (and Judo more widely) should research this area and try and determine if there is an actual difference and if so, why it is occurring and when.

It would also be interesting to compare these participation levels to other sports such as Tennis, Dance, Rugby, Wrestling, TKD or Karate. We might find that Judo participation levels by females and at the Dan Grade may be good rather than poor. The percentage of girls aged 14-15 that do not participate in any active sports, on a weekly basis, is around 15% to 20%  (Balding, J. (2004). Young people in 2003. Exeter: Schools Health Education Unit.), so how would this fit with our numbers?

The Dan grade register data also has information such as area, club and date of the grading, analysing this information shall be the subject of later posts. You may also wish to take a look at the data yourself, the part that formed the basis of this post is available at http://www.swivel.com/data_sets/show/1017786 it has the data and some nice charts too.

The anatomy of an elite level Judo match (Craig Fallon at 2003 European Judo championships).

Craig Fallon
Photo by M Lee

Recently a colleague of mine sent me a study he conducted some time back observing British fighter Craig Fallon in action at the 2003 European Championships. Dave Elmore analysed all the fights Craig had on the day against Paischer, Uematsu, Morokhovets, Nazaryan and Khergiani. He carefully recorded the time spent in the following categories:

  • Adjusting Judo Gi
  • Gripping
  • Ne – Waza (grappling)
  • Hajime
  • Matte
  • Attacking – Tachi – Waza
  • Defending Tachi – Waza

Dave is the Judo Development officer at the University of Wolverhampton in the UK. He also runs the very good Advanced Apprenticeship Judo Blog. He looked at the data on a fight by fight basis and also overall, which produced the following chart:

As you can see from the chart, very little time was spent by Craig Fallon attacking in Tachi Waza. A majority of the matches was taken up with Ne Waza, Kumi Kata and adjusting Judo suits. Of the 19 minutes and 23 seconds spent in the competition, only 33 seconds of that time was actual attempts at throwing. Now there are lots of reasons for this, not least of all the speeed at which attacks happen. What stands out is the percentage of time that Craig spent fighting for a grip (29.41%), which shows the importance kumi kata perhaps.

31.30% of Craig Fallon’s time was spent in Ne Waza, it would be interesting to conduct a wider study looking at an entire category or event to see if this is a feature of Craig Fallon’s Judo or of light weight Judoka, or not.

The amount of time spent adjusting the Judo suits is also an eye opener, not an area of Judo that I have seen recorded before and as the chart shows quite a large part of the fight was spent just getting dressed (26.57%). Again this may be a feature of the fighting style of Craig and his opponents, it would be interesting to see if this amount of time is consistent across weights and genders.

If these numbers were to be proven to be standard across Judo, then it would have implications for coaching. Kumi Kata is growing in acceptance as an important skill that must be practised, this study supports this idea. This study could be used to justify increasing the amount of time drilling and practising kumi kata in club training sessions.

The amount of time spent adjusting the Judo Gi may also be important in terms of recovery time between segments of action during a match. Further study might provide suggestions to train for shorter bursts of action, or perhaps more grip related training similar to that shown on the Judo-Sport blog recently (via www.planetjudo.com).

Dave has kindly provided me with his data and I shall be looking at it in more detail and will post a follow up in a future article.

A quick test of notation reliability.

I am, as some are aware, presently researching the attack rates of athletes in the 2008 Olympic Judo tournament in Beijing. To do this I am notating the attacks made by each athlete and analyzing the results. As with many forms of analysis there are issues to be addressed around the calidity of the data. One of which is how accurate your recording is, in this post I would like to invite you to help my project by notating a short video from YouTube and emailing me your result, this will be helpful so I can see what the variations in the data are. I shall post the findings of this experiment afterwards.

Notation Methodology:

Take a sheet of paper, draw a line down the middle of the page and notate as follows:

On the paper based hand notation form each attack will be recorded as a vertical line “|” if the
opponent does not touch the floor with another part of the body other than the feet. A “+” will be
recorded if the attack does cause the opponent to touch the floor with another part of their body but
no score is given. The form has two columns, one for each player, the “|” is placed in the
appropriate column for each player. If a score was given, no “|” is marked,  a letter indicating the
score is written instead. These are K for Koka,  Y for Yuko, W for Wazari, I for Ippon and P for a
penalty. When Matte was called, the recorder moves down one line on the notation form. If no
attack has been made a horizontal line is recorded “-”, is neither player has attacked, then both
columns have a “-” recorded. Each period between the referee’s “Hajime” call and “Matte” call is
termed a segment and recorded on a separate line on the form.

If you could forward your notation to me (lw@judocoach.com) that would be terrific, it will be interesting to see how many people participate and also how much the data varys between people. I shall keep your data anonymous of course.

Many Thanks,

Lance.

Ages of medalists at 2009 Judo World Cup events.

Airborn combatIn this post we shall briefly look at the ages of the Judoka competing at the latest Judo World Cup events in Europe. The two events are the 2009 – World Cup – Prague, and the World Cup Warsaw – 2009. Prague was a womens event, Warsaw a mens event.

Method:

  • Ages and results were obtained from the JudoInside website for both events.
  • Data was analyzed for medalists only
  • Statistics between winners and silver and bronze medalists is compared.

Results:

  • 24.95    Average Age of medalist
  • 34    Max oldest medalist
  • 17    Min youngest medalist

Winners/Gold Medalist:

  • FEMALE:  Average age: 25.14(+-5.67)    Max: 34    Min: 19
  • MALE: Average age: 26.2(+-4.66)    Max: 32    Min: 21

Non-Winners/Silver and Bronze:

  • FEMALE: Average age: 25.15(+-3.62) Max: 31 Min: 17
  • MALE: Average age: 24.4(+-3.62) Max: 33    Min: 20

Discusssion:

The sample size for here is very small, a mere 52 data points (of a possible 56).The analysis is in no way comprehensive.

Target age of players to compete in these events:
The ideal target age to be ready to compete in these events is between  19.47 and 30.81 for women and 21.54 and 30.86 for men. How this relates to the 2012 games is a matter of debate, but these target ages suggest either that athletes winning in London will be approximately 28, or that the older athletes competing today will be retired by London 2012, thereby keeping average ages down.

The age span is quite large 17-34, with average winners age being 25-26 years of age. This perhaps indicates younger athltetes need to spend several years at this level before winning. This could be tested by a further examination of ages for those who did not make the medals potentially.

Talent ID:
For countries looking for players to medal at London 2012 this brief analysis could suggest that they need to be focusing on players who are presently around 22 years of age. For the next Olympic games in 2016 a further talent squad could/should be identified who are approximately 18 years old. This could be extended to 2020, 14 years old now.