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Re: [RC] Completion rate by Wt division - Truman Prevatt

What needs to be done is break it down to three ride categories - LD, "50" and one day 100. Then each weight division in each should be calculated. I actually did this some time back for a season and came to the same results with an overall average. I also found that for finishing time in LD's it didn't really matter at least with the numbers available for a season. It started to matter at "50." There weren't enough HW's doing 100 to get a large enough sample size to really say much.

I think I have all the data I need '96 through '06 so if I can break loose some time - I'll look at it.

Truman

Michael Maul wrote:
I noticed the difference too and decided that Truman would let me know if I was wrong. He did and I was off a little on how long that would take... :-)

Truman is certainly correct.

I considered looking at the 12 years of data and whether distances like 100 miles vs LD made a difference but given my present "job", I don't have the time.

Doing simple averages as I did is OK when the results are close but real statistical analysis is needed when they are not.

What it means - I'm not sure other than it went from lightest - Juniors to heaviest - in completion rates.

Mike


--- On Wed, 10/22/08, Michael Maul <mmaul@xxxxxxxxx> wrote:

From: Michael Maul <mmaul@xxxxxxxxx>
Subject: Re: [RC] Completion rate by Wt division
To: "ridecamp" <ridecamp@xxxxxxxxxxxxx>, "Truman Prevatt" 
<tprevatt@xxxxxxxxxxxxxx>
Date: Wednesday, October 22, 2008, 10:50 AM
--- On Wed, 10/22/08, Truman Prevatt
<tprevatt@xxxxxxxxxxxxxx> wrote:

From: Truman Prevatt <tprevatt@xxxxxxxxxxxxxx>
Subject: Re: [RC] Completion rate by Wt division
To: "Michael Maul" <mmaul@xxxxxxxxx>,
"ridecamp" <ridecamp@xxxxxxxxxxxxx>
Date: Wednesday, October 22, 2008, 9:23 AM
While these "numbers look close" there is a
significant statistical difference between HW and the other weight divisions.
One
might suspect this since the difference between MW and HW (2.4%) is
8
times greater than that between the other categories (.3%).

The Strong Law of Large Numbers is a wonderful
property -
it allows one to make mathematically valid decisions from statistics
that
appear "close" when the sample sizes become large
which
is the case here. When you calculate the standard errors for the four
categories
and then compare the number of "sigmas" apart the
completion probabilities you find for the three categories, FW, LW and MW the
maximum
simgage (FW to MW) is 1.2 which is well within expected statistical
variation at random. However, when you compare the simage of HW to
MW it
is on the order of 4.5 sigma - which equates to a probability of
less
than .001 for the sample mean for HW actually coming from the MW
category.

These data show to a confidence of greater than 99%
that
the pull rate for the population of horses carrying heavyweight
riders is
higher than that for any other weight division. These data also
show
that the difference between the pull rates between MW, FW and
LW are
statistically insignificant based on these sample
sizes. In
order to see if the statistics of the pull are statistically
different
for MW, LW and FW - more data would be needed. To conclude to a 99%
confidence that say the pull rate of FW was greater (or less) than a
sample
size of over 116000 for each would be required.

Truman

Michael Maul wrote:
There was a recent post - either on the
member's
forum or RC - that 
commented on the completion rate
by wt. division at the NC.

It showed some differences by wt division so I
decided
to see if that 
was true for a whole season's
rides.

In 2006

Div     starts  completions     % Comp
FW      4720    4104    86.9%
LW      6558    5677    86.6%
MW      4747    4096    86.3%
HW      3087    2589    83.9%
Jr      815     715     87.7%



There's a slight drop in completion rate for
HW
and a slight increase
for Juniors but
overall - it looks pretty close. The average
that
year for all riders
was

Mike

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"The trouble with fighting for human freedom is that one spends most of one's time defending scoundrels. For it is against scoundrels that oppressive laws are first aimed, and oppression must be stopped at the beginning if it is to be stopped at all." H. L. Mencken


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Replies
Re: [RC] Completion rate by Wt division, Michael Maul