Tag Archives: rules

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.