A Puzzle

As our summer series is coming to an end I've noticed an interesting thing in Sailwave. Our racers are broken up into four fleets. If I score everyone together I get one result. However, I get two different results if I score everyone together but in separate fleets compared to if I score everyone separately in fleets.

Have a look at these two sets of results:

http://www.torontowindsurfingclub.ca/racing/wed_results/twc-wed-results.htm

http://www.torontowindsurfingclub.ca/racing/wed_results/twc-wed-avgs.htm

Notice the difference in the rankings of the competitors in Gold fleet. The separated fleet results don't match with the overall results. Anyone have any suggestions as to why this shows up?

Cheers,

Nick Cox

Good Morning Nick,
The Rankings can change between the two methods of scoring.
Because with the seperate fleets the scores for DNC, DNS, DNF etc will be different, but also if a Gold boat is say 5th with two red boats in front, scored as one fleet he is 5th as seperate fleets he is 3rd. If all the Gold fleet always finished in fron of the red fleet ans so down the fleets there would be no differnce.
Many classes that I have dealt with use the first method scoreing as one fleet then picking out the 1st, 2nd and 3rd from each fleet from the overall results.
Which way is right, your SI's should cover this but they often don't. There are good arguments for both ways.
Dave Vinnell
Galway Bay Sailing Club

···

----- "Nick" <c1v1equalsc2v2-sailwave@yahoo.ca> wrote:

As our summer series is coming to an end I've noticed an interesting
thing in Sailwave. Our racers are broken up into four fleets. If I
score everyone together I get one result. However, I get two different
results if I score everyone together but in separate fleets compared
to if I score everyone separately in fleets.

Have a look at these two sets of results:

http://www.torontowindsurfingclub.ca/racing/wed_results/twc-wed-results.htm

http://www.torontowindsurfingclub.ca/racing/wed_results/twc-wed-avgs.htm

Notice the difference in the rankings of the competitors in Gold
fleet. The separated fleet results don't match with the overall
results. Anyone have any suggestions as to why this shows up?

Cheers,

Nick Cox

This is the difference between an scored ranking in a group and ranking extracted from the general ranking.
When groups have different characteristics (like in Micro Class Protos 450 kg, Racers 540 kg, Cruisers 560 kg and smaller rig), an extracted ranking doesn't give a good picture of the level of the competitors. In race 1 of the Worlds 2003 http://www.microclass.org/results/MC03.html , Protos failed, 2/3 are DNF, Racers 1/2, Cruisers 1/3. This race makes that the surviving Racer and Cruisers take a huge advantage of this situation, with one result far above expectation, while retiring Protos are heavily penalized.
In this situation, better score within the group.
Otherwise, if boats are randomly spread in the groups, there could be some differences between the rankings, but no more than some swaps...

Phil

···

----- Original Message ----- From: <davenow@eircom.net>
To: <sailwave@yahoogroups.com>
Sent: Tuesday, September 29, 2009 9:35 AM
Subject: Re: [sailwave] A Puzzle

Good Morning Nick,
The Rankings can change between the two methods of scoring.
Because with the seperate fleets the scores for DNC, DNS, DNF etc will be different, but also if a Gold boat is say 5th with two red boats in front, scored as one fleet he is 5th as seperate fleets he is 3rd. If all the Gold fleet always finished in fron of the red fleet ans so down the fleets there would be no differnce.
Many classes that I have dealt with use the first method scoreing as one fleet then picking out the 1st, 2nd and 3rd from each fleet from the overall results.
Which way is right, your SI's should cover this but they often don't. There are good arguments for both ways.
Dave Vinnell
Galway Bay Sailing Club

----- "Nick" <c1v1equalsc2v2-sailwave@yahoo.ca> wrote:

As our summer series is coming to an end I've noticed an interesting
thing in Sailwave. Our racers are broken up into four fleets. If I
score everyone together I get one result. However, I get two different
results if I score everyone together but in separate fleets compared
to if I score everyone separately in fleets.

Have a look at these two sets of results:

http://www.torontowindsurfingclub.ca/racing/wed_results/twc-wed-results.htm

http://www.torontowindsurfingclub.ca/racing/wed_results/twc-wed-avgs.htm

Notice the difference in the rankings of the competitors in Gold
fleet. The separated fleet results don't match with the overall
results. Anyone have any suggestions as to why this shows up?

Cheers,

Nick Cox

------------------------------------

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Thank you Dave,

I'll discuss this with our Race Committee chair and see which method we should adopt.

Cheers,

Nick

···

--- In sailwave@yahoogroups.com, davenow@... wrote:

Good Morning Nick,
The Rankings can change between the two methods of scoring.
Because with the seperate fleets the scores for DNC, DNS, DNF etc will be different, but also if a Gold boat is say 5th with two red boats in front, scored as one fleet he is 5th as seperate fleets he is 3rd. If all the Gold fleet always finished in fron of the red fleet ans so down the fleets there would be no differnce.
Many classes that I have dealt with use the first method scoreing as one fleet then picking out the 1st, 2nd and 3rd from each fleet from the overall results.
Which way is right, your SI's should cover this but they often don't. There are good arguments for both ways.
Dave Vinnell
Galway Bay Sailing Club

----- "Nick" <c1v1equalsc2v2-sailwave@...> wrote:
> As our summer series is coming to an end I've noticed an interesting
> thing in Sailwave. Our racers are broken up into four fleets. If I
> score everyone together I get one result. However, I get two different
> results if I score everyone together but in separate fleets compared
> to if I score everyone separately in fleets.
>
> Have a look at these two sets of results:
>
> http://www.torontowindsurfingclub.ca/racing/wed_results/twc-wed-results.htm
>
> http://www.torontowindsurfingclub.ca/racing/wed_results/twc-wed-avgs.htm
>
> Notice the difference in the rankings of the competitors in Gold
> fleet. The separated fleet results don't match with the overall
> results. Anyone have any suggestions as to why this shows up?
>
> Cheers,
>
> Nick Cox
>
>
>