Re: Finding the peak

["John Racine" <gaijira@tky2.3web.ne.jp>]

This topic came up a couple of months ago, but I've been too busy to read
it....

Mr. Walker's analysis seems pretty solid, but I'd like to see a break down
by highest achieved rank.  That is:  What was the peak age for all those
achieving Yokozuna status?  How about ozekis, the rest of sanyaku, upper and
lower maegashira?  There might be some interesting differences there.

Sukebeejima


----- Original Message -----
From: "G. Jay Walker" <walker@nhrc.navy.mil>
To: <sumo@sun01pt2-1523.statgen.ncsu.edu>
Sent: Wednesday, December 11, 2002 8:36 AM
Subject: Finding the peak


> (warning - pseudo-stat geek post)
>
> At what age do rikishis peak?  How rapidly do they decline after reaching
their peak?  What percent fight effectively into their 30's?
>
> I use a rank/record type of rating system occasionally.  It lacks a bit of
the accuracy of the bout-by-bout systems others have devised, but it takes a
lot less time to set-up and calculate.  As an analytical tool, it wouldn't
qualify as a sharpshooter's rifle, but it does kind of resemble an elephant
gun.   For more precise questions needing a sharpshooter's accuracy - say
like comparing the careers of two rikishi - you may want to indeed grab your
sharpshooter. But if you're trying to answer a big broad question - like at
what age do rikishis peak? - than maybe it's okay to use an elephant gun to
bring down an elephant.
>
> Using my rank/record system, I've developed lists of the top 40 rikishi
going back quite a few years.  For any given year, I awarded 8 points to a
rikishi if he finished in the top 5 for the year, 7 points if he ranked 6th
through 10th, down to 1 point for those ranked 36th to 40th.  Those ranked
below 40th received 0 points.  So Kotonowaka, who ranked 18th this past
year, earned 5 points at age 34.  Daizen, ranked 34th, earned 2 points at
age 37.
>
> The study group was all the top-division rikishi born in the 1960's,
starting with Asahifuji (born July 6, 1960) through Asanosho (born December
23, 1969) - a total of 73 rikishi.  They started reaching the top 40 in 1981
and a few still remain in the top 40 through this year (Kotonowaka,
Akinoshima, Daizen, Asanowaka).  However, all have now reached at least 33
years, so they shouldn't present a problem in determining the peak.
>
> The three columns below show the age, the total number of rikishi  who
ranked in the top 40 at that age (out of the 73 in the study) and the total
number of points they earned at that age:
>
> Age
> 20 6 22
> 21 9 48
> 22 18 84
> 23 28 123
> 24 33 153
> 25 44 191
> 26 44 222
> 27 48 225
> 28 42 189
> 29 37 159
> 30 25 107
> 31 19 75
> 32 11 48
> 33 10 41
> 34 8 23
> 35 6 17
> 36 4 11
> 37 2   3
> 38 0   0
>
> (Note - a few more points might be added to the 33-and-over totals if
Kotonowaka, Akinoshima and Asanowaka can stay in the top division.)
>
> Perhaps these results don't reflect any more that what an astute observer
would pick up from a few years of watching sumo, but they do quantify such
observations.  The peak is usually reached at 26 or 27.  Most young rikishi
don't make their mark until 23 or 24.  There is not a 'plateau' after
reaching the peak, but in fact a significant decline between the ages of 27
and 30.  For every rikishi performing in the top division at age 27, only
about half will be there at age 30; only about 20% at age 33.
>
> If form holds (and there are exceptions), collectively one would expect
the 76'ers (those born in 1976, including Chiyotaikai, Tochiazuma,
Kotomitsuki and Wakanosato) not to show that much improvement in their
remaining careers.  While there may be an individual breakthrough or two, at
age 26 they are more likely about as good as they'll ever be.  On the other
hand, for Asashoryu at age 22. well, you can look at the table and draw your
own conclusions.
>
> Another study using a more accurate weapon than an elephant gun might
alter a few of the results found here in some modest ways. And as time moves
on, results from rikishis born in the 1970's might vary from these results
(there are some early indications that the 27-to-30 decline is becoming less
pronunced).  But I don't think they would change any of the main
conclusions.
>
> -George W.
>
>