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PY Numbers (again)

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Hector View Drop Down
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Post Options Post Options   Quote Hector Quote  Post ReplyReply Direct Link To This Post Topic: PY Numbers (again)
    Posted: 05 Jan 10 at 1:27am
Sorry above not very clear - I meant to say that at our club, the laser h'cap is bad against virtually every other well sailed class. But we understand that as a 'primary number', its somehow set in stone and indeed if we suggest it needs raising, then the rest of our returns are somehoow deemed untrustworthy!
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 05 Jan 10 at 8:13am
Originally posted by Hector

Sorry above not very clear - I meant to say that at our club, the laser h'cap is bad against virtually every other well sailed class. But we understand that as a 'primary number', its somehow set in stone and indeed if we suggest it needs raising, then the rest of our returns are somehoow deemed untrustworthy!


Your understanding is incorrect. Primary numbers are the ones with the best statistical base, so if you have, with enough numbers to make reasonable estimates, say three classes with secondary or rr numbers, and one with a primary number then it makes more sense to change all the secondary classes up 10 points than change the primary number down 10 points. That way unchanged numbers are more likely to be correct.

But if you have three or 4 classes with primary numbers and need to change one then you are should do... The RYA don't throw numbers out because they don't like the look of them. What they may do, I think, is to add a correction: if your club return suggests that most classes go down 10 points and one or two stay the same they may adjust your numbers so that the average stays closer to what it is now.

The Laser handicap is one of those bizarre things... One of the things that does it down is the Laser sailors tendency to race each other in large handicap fleets: they'd rather be 10th and 1st Laser than 2nd and 2nd Laser. But we alter the Laser PY at my club: we've got someone with a good grasp of stats doing the handicaps and he does good work, although we sometimes disagree over the handicap of my boats - he's inclined to be a bit over generous - I suspect because he knows how competent I am sailing as forward hand he doesn't make enough allowance for my rather lesser ablity when pointing the boat myself!

Edited by JimC
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maxibuddah View Drop Down
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Post Options Post Options   Quote maxibuddah Quote  Post ReplyReply Direct Link To This Post Posted: 05 Jan 10 at 8:23am
what i meant to say about the laser py was that it is ok as an averages boat, never really excelling in any conditions, which should mean that its results are ok over a long series but it will never do well at one off events.
Everything I say is my opinion, honest
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Post Options Post Options   Quote chrisg Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 10 at 10:34am
Originally posted by Hector

Sorry above not very clear - I meant to say that at our club, the laser h'cap is bad against virtually every other well sailed class. But we understand that as a 'primary number', its somehow set in stone and indeed if we suggest it needs raising, then the rest of our returns are somehoow deemed untrustworthy!


Hector, please dont think like that. As Jim C said, all numbers are relevant data for the RYA so please dont think that because you have changed a primary PY nunber your club results would seem untrustworthy. Please make sure your club sends all handicap race results back if possible.
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 10 at 3:36pm
Here's a list of class average placings at the Bloody Mary over the last 8 years. Pick your handicap bandits...

Bloody Mary Average Placings

The fewer entries for each class over the years the less meaningful the average is of course.
Its interesting how very different the number of boats of each class that turn out to the BM (and other major handicap events) is to the relative popularity of the classes when calculated by Champs entries or claimed UK sales. There are links on the page to tables of BM popularity, Champs popularity and UK sales. The UK Sales table, it has to be said, is rather unreliable as much of the data supplied to the RCR is incomplete, inconsistent or just plain missing.

I've included Standard deviation figures on the page: this is an indicator of how varied results are... Most of them are, frankly, statistically fairly meaningless, but I must say that Laser and Laser Radial results suggest that statistically there is a question about their handicap under QM winter conditions. If I were the QM handicapper I would take a good luck at the quality of entry in those fleets... If they have National level sailors coming out and doing no better than that then maybe there is an argument for giving the Laser sailors an increased handicap on that water. I'd probably also have a bit of a think about the I14, National 12 and Firefly handicaps in the other direction. Its interesting actually, because my home club is near QM with similar water, and we have adjusted both Laser and N12 handicaps (we don't have I14s or Fireflies in significant numbers). Maybe Lasers like sea and waves better than N12s?

Edited by JimC
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Post Options Post Options   Quote blaze720 Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 10 at 5:19pm
Here are some of Jims BM numbers just re-sorted - anything less than 5 entries over this time removed  !    It must be a boring afternoon ....

Class % Place Finishes StdevPop.
Thames A Rater 5.0 6 4.4
National 12 21.8 44 21.3
2.4m 24.5 15 27.9
Firefly 28.1 30 22.2
Europe 28.6 18 15.3
Gp14 29.6 39 26.6
International 14 29.9 37 22.7
Solo 34.2 42 24.5
Fireball 34.3 36 23.9
Phantom 34.9 17 21.4
Cherub 35.9 10 35.7
National 18 36.8 5 16.2
Merlin Rocket 37.9 110 28.6
505 38.1 24 24.2
Scorpion 38.8 9 18.8
49er 39.1 24 29.7
Lark 40.6 23 28.4
Rs400 40.9 84 22.6
Finn 41.6 10 23.9
Rs200 44.4 94 26
Rs800 44.9 34 24.5
Hornet 46.4 22 13.5
Enterprise 47.6 36 30.3
Graduate 48.5 9 29.4
Int. Moth 49.0 10 28
Albacore 50.1 16 26.2
Rs K6 51.6 21 18.5
Bosun 51.9 9 34.5
Miracle 52.9 7 34.1
Rs600ff 53.3 5 30.6
420 53.5 40 24.6
470 53.9 5 25.9
Rs300 54.0 10 25.5
29er 54.3 41 23.5
Musto Skiff 58.0 9 15.9
Laser 5000 59.1 7 25.7
Comet 59.3 17 20.4
Buzz 59.9 12 31.9
Topper 59.9 56 22.8
Blaze 60.4 7 20.1
B14 60.7 19 23.3
Rs600 62.7 17 20.5
Rs700 64.2 20 19.6
Laser 4000 66.5 22 18
Iso 66.7 16 22.4
Vortex 68.1 13 21.4
Contender 68.5 7 26.4
Yeoman 69.3 15 28.3
Int. Moth - Foil 69.7 10 37.2
Tasar 70.9 13 13.3
Laser 71.8 105 17.8
Laser Radial 76.9 67 16.1
Wayfarer 78.6 10 24.3
Laser 2000 80.3 18 23
Rs Feva 80.4 10 20
Laser 3000 85.7 10 20.4
Laser Ii 88.0 8 10.9
Topper Omega 89.8 6 2.5

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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 10 at 5:25pm
Originally posted by blaze720

It must be a boring afternoon...

Yeah well, someone slid into my parked van and trashed the rear a few days ago, and I don't reckon I could push the motorcycle up the icy hill encumbered with sailing gear, so going to the sailing club is impossible.
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Jon Meadowcroft View Drop Down
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Post Options Post Options   Quote Jon Meadowcroft Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 10 at 10:09pm

Interesting analysis.  N12s and Fireflies should be suited to pursuit racing as they get to start before the scrap that goes on behind...

The same analysis on say the Grafham GP or the Steve Nicholson race is what you really need to understand the PY.  My experience is that I would back a 12 to win the Bloody Mary or the London Boat Show race, but I would not back a 12 to win a big general handicap race - the rare successes in these events tend to be when the fleets are small.

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