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PY Numbers for 2017

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Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Topic: PY Numbers for 2017
    Posted: 07 Mar 17 at 11:32am
It always has been 'only handicap racing'.
It's a modern tendency to have loads of new 'classes' with zero class racing.
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 17 at 12:31pm
Originally posted by E.J.

No the variables are endless;

A few I can think of,

Maybe it was a year of conditions that don't suit the laser
Maybe some clubs reclassified them mediumto slow fleet and now it against solos
Maybe a chunk of the top sailors bought aero or zero
Maybe lots of people learnt to sail and bought lasers
Maybe lots club fleets were absorbed into the handicap fleet and the competition was hot.
Maybe a mixture any or probably other


But:
1. Should be damped/filtered out.
2. Why would that change anything, unless implying a relative drop in standard?
3. An absolute drop in standard.
4. An absolute drop in standard.
5. A relative drop in standard.
None of which is reason to raise the PY - if the aim is to be a yardstick of boat performance.
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Post Options Post Options   Quote E.J. Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 17 at 12:43pm
The aim, I think is not to rate boat performance (design) but rather fleet performances. Again we circle back to the fact that none of these variables are filtered, and PY is not designed to enable this. All classes are relative to each other so the laser has relatively performed lower than it PY, but clearly it has not performed lower as a design.



Edited by E.J. - 07 Mar 17 at 12:45pm
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Post Options Post Options   Quote jeffers Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 17 at 12:56pm
Originally posted by A2Z

Originally posted by E.J.

No the variables are endless;

A few I can think of,

Maybe it was a year of conditions that don't suit the laser
Maybe some clubs reclassified them mediumto slow fleet and now it against solos
Maybe a chunk of the top sailors bought aero or zero
Maybe lots of people learnt to sail and bought lasers
Maybe lots club fleets were absorbed into the handicap fleet and the competition was hot.
Maybe a mixture any or probably other


But:
1. Should be damped/filtered out.
2. Why would that change anything, unless implying a relative drop in standard?
3. An absolute drop in standard.
4. An absolute drop in standard.
5. A relative drop in standard.
None of which is reason to raise the PY - if the aim is to be a yardstick of boat performance.

Not correct. As the PY is based on results it will be a yardstick of the people sailing as well as the boat performance. This is why some boats that have has significant development recently are getting slower not faster.

I do believe they take the previous 2 or 3 years data into account to help dump out year on year variations with less emphasis given on the older data.
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Post Options Post Options   Quote zeon Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 17 at 12:59pm
That's what I was told when I asked a member of the committee a few years ago.
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 17 at 1:16pm
Just because you dinghy types haven't 'done' something, doesn't mean it's not possible.

'Average" how do you think you work it out? You add them all up and divide by the mean. Or to start with you work it out on weight.

This formula of peakys works well if you tweak it a bit, and multiply the sail size by ten to get average weight and you'd be surprised how close it is to what exists at the moment.

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Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 17 at 1:45pm
Originally posted by zeon

That's what I was told when I asked a member of the committee a few years ago.

I think this is a lot of the problem, the data and process are not open, so people cannot see the detail of what's going on. This breeds distrust.

It would also be useful to be able to drill into the data and see why things are changing year-on-year.
Let's say a club with a couple of Vareos. The PY has gone up by 14.
Why is that?
IS it a valid change for my club?

It might be that last year, the only Vareo returns came from clubs dissimilar to mine? Maybe the returns come mostly from inland or maybe the boats they are racing against have changed? Maybe it's suffered a shift in courses?
Interesting to note that according to its wiki page, the US DPN system has it slower than a Laser. So it might need another 10 points yet?
How are the US numbers generated?
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Post Options Post Options   Quote Oli Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 17 at 2:01pm
if you don't trust it for your club what solution is there?







adjust it locally perhaps?
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 17 at 2:19pm
Originally posted by E.J.

The aim, I think is not to rate boat performance (design) but rather fleet performances. Again we circle back to the fact that none of these variables are filtered, and PY is not designed to enable this. All classes are relative to each other so the laser has relatively performed lower than it PY, but clearly it has not performed lower as a design.


No (but see below Wink) the aim is to "enable clubs to allow boats of different classes to race against each other fairly. The RYA actively encourages clubs to adjust handicaps where classes are either under or over performing compared to the number being used." so to rate the boats not the sailors (allowing local variations where prevailing conditions are more or less suited to the boat on question). The fact is that there is no practical way to prevent the sailor from affecting his boat's performance so the PN does actually end up reflecting the 'fleets' performance as you say. But that's the consequence of the imperfect system with too few results being returned to make it a 'proper' statisticial analysis rather than the aim of the system.




Edited by Sam.Spoons - 07 Mar 17 at 2:20pm
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Post Options Post Options   Quote Cirrus Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 17 at 2:28pm
It is an extremely popular and predictable annual event .. the 'PN discussion' that is ..

Firstly the system does not pretend to assess / predict / represent what any class is capable of..... I think this is the real misunderstanding of the 'raw' PN system by many out there.   At best it is indicative at worse misleading.   This is pointed out each and every year.

It simply crunches as much data as possible to give a rough indication of the relative speed of the average example of each class.  What is there not to understand ?  You should know as well as the next pundit that in crude terms HALF of each class should be able to sail their boats FASTER in relative terms than the avearage.  Equally HALF of the owners don't sail as fast as the AVERAGE owner as well.   This stuff is not as straightforward as some think by a long way.

Go much beyond this deliberate simplicity and you get into the science (or otherwise) of sample selection.  If you want to know what a good example of a boat with a good helm is CAPABLE of  then you need to stop 'weighing' the amount of date involved and kiddling yourself and others that 'more is better' ... and well 'it MUST surely be better'  ...

Really really want to assess boat capability ?  Now that is something only partially related to the 'raw average' of any fleet ....  The sample you need to use may well be a subset of the 'mass' date you could use but you cannot simply get away from the need to have a structured sample.  It really is that basic.    Now we could 'discuss' how the sample should be composed to get closer to the 'capability' of any particular class but that is very much a different discussion.

'till another year then .... Wink
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