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Old June 23rd 09, 03:11 PM posted to rec.aviation.soaring
rhwoody
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Posts: 23
Default US contest scoring formula is broken

On Jun 23, 7:51*am, T8 wrote:
On Jun 23, 9:18*am, Andy wrote:





On Jun 22, 11:08*pm, Steve Koerner wrote:


Then a bizarre compression comes into play for slower finishers. *The
seventh place pilot flew a mere 67 miles at 23.33 mph and received 76%
of the winners score. *That’s absurd. *He flew only about one third of
the speed and distance that the second place finisher flew yet scored
a mere 70 fewer points.


This in part results from a change in 2007 that changed Maximum
Distance Points (MDP) from 400 to 600. The relevant rules (for MAT and
TAT - similar for AST) a


* * * * 11.6.6 Maximum Speed Points:
* * * * * * *MSP = STF * (600 + 500 * SCR) (but not greater than STF *
1000)
* * * * 11.6.7 Maximum Distance Points:
* * * * * * *MDP = MSP * (0.8 - 0.2 * SCR)
* * * * 11.6.8 Points for Finishers:
* * * * * * *POINTS shall be equal to the largest of the following
three quantities:
* * * * * * *MSP * SPEED / BESTSPD
* * * * * * *MDP + 30 + MSP * 0.2 * ((SPEED/BESTSPD) - 0.4)
* * * * * * *MDP + 30


As I understand it, the basic idea is that the rule makers (with pilot
input) are trying to make sure that pilots who have a landout can stay
somewhat competitive (See: 11.6.8 - dropping 600 points on a day is
hard to make up - 400 is still hard, but less so). There are also
provisions for devaluing tasks with lots of landouts (more than 20% -
see 11.6.6). Lots of landouts are thought to correlate to a higher
"luck factor". Short tasks are also devalued under similar logic.


The simplest scoring formulas would be to set Maximum Speed Points
(MSP) to 1000 and Minimum Distance Points (MDP) to zero and to get rid
of Scored Completion Ratio (SCR) and Short Task Factor (STF). What
this would mean is that if you finish, you get a score that is
directly proportionate to your percent of the winner's speed - no
matter how slow you go. If you land out you get zero. An alternative
is to to keep the idea of MDP (but we need to pick a number - 200,
400, 600, 800?) and relax the constraint that the best landout has to
get fewer points that any finisher. This allows us to keep the idea of
strict proportionality for any speed finisher. Under this scenario you
could see your score drop by a lot if you you are slow and finish
rather than landing out (because MDP exists, finishers whose speed as
a percent of the winner's speed is less than MDP/1000 could score less
than a long landout). This may be a bad idea as it encourages landing
out.


A third alternative is to pin any finisher's score that is less than
MDP to MDP - but this introduces the possibility that the bottom of
the scoresheet is populated with pilots who have identical scores
because they can't get above MDP. The lower you make MDP, the less
likely this is, but to avoid it for the Montague example described by
Steve MDP would need to be 300 points - which is less that it has ever
been in the rules. Obviously, that specific situation doesn't come up
often, and when it does its usually a funky day or a situation where a
pilot had something odd happen on course. It can also result from
cutting short at MAT (particularly if no turnpoints are assigned) or,
to a lesser extent, a TAT course.


I agree that the Montague example seems extreme, so it may warrant
review. It seems to me that all the alternatives have some tradeoffs
though.


9B


It's the use of MDP in formulas 2 & 3, without regard to how many
miles any given pilot actually flew, that's causing problems.

Agreed that our scoring rules are getting a little dense. *I'm
curious: how are European comps scored? *Anyone got a link?

-T8- Hide quoted text -

- Show quoted text -


Has anyone thought of getting back to basics - by that I mean getting
rid of TAT and all of the follow on tasks to POST - and fly only AST -
Assigned Speed Task - start gate, finish gate, all competitors fly the
same turnpoints, finish gate - fastest pilot wins?