Averages. CMA. Greensheet. Rolling.

[Cast1rn]

1 minute ago, arnieg said:

Firstly the CMA is 4 as the point of the calculation is to normalise for the number of rides taken, and secondly if you are going to suggest I am mathematically challenged you really should be aware that I have a degree in Maths.

1 hour ago, arnieg said:

Not necessarily, it depends which heats you take those rides in.

Would Never suggest your were mathematically inept. My statement was if I scored 3 in 3 rides 16 times my average based on this equation used would be 4 which mathematically speaking would be incorrect??

"You stated it depends which heats you take those rides in"

I can't see how scoring 3 points in a meeting would make a difference on what heat the rider scored them in.

I'm not looking to belittle or argue with anyone, what I want to know is surely using the equation that has been put out here cannot be done because it is mathematically wrong.

 

 

[Chadster]

On 6/25/2023 at 4:31 PM, Cast1rn said:

"You stated it depends which heats you take those rides in"

I can't see how scoring 3 points in a meeting would make a difference on what heat the rider scored them in.

I'm not looking to belittle or argue with anyone, what I want to know is surely using the equation that has been put out here cannot be done because it is mathematically wrong.

 

I don't think the formula is mathematically wrong, but it does produce anomalies, as you've pointed out with the reserves. You could also have pointed out that it takes no notice of the two riders who take part in heat 15 and thus have five rides, or that a reserve can take seven rides. The solution is to miss out the times 4 bit. So the reserve in your example would have an average of 1 point per ride, a heat leader who rode regularly in heat 15 and scored 13 points in every match would have an average of 2.60. I believe they use, or used this system in Sweden and perhaps elsewhere.

 

[Cast1rn]

5 hours ago, Chadster said:

 

The problem is that if you just did an average based on points per heat average, which would be a completely accurate. You would have to go to 3dp to get separation of the riders or you could have a lot of 1.0 riders and imagine the excitement of building a team to a score of 12 where your squeezing in a 1.789 and a 2.783.

 

[arnieg]

8 hours ago, Cast1rn said:

The problem is that if you just did an average based on points per heat average, which would be a completely accurate. You would have to go to 3dp to get separation of the riders or you could have a lot of 1.0 riders and imagine the excitement of building a team to a score of 12 where your squeezing in a 1.789 and a 2.783.

 

Which is exactly what they do in Sweden

https://www.svemo.se/vara-sportgrenar/start-speedway/resultat-speedway/resultat-bauhausligan-speedway

(Go to aktuella snitt)

Edited June 27, 2023 by arnieg

[Cast1rn]

2 hours ago, arnieg said:

Which is exactly what they do in Sweden

https://www.svemo.se/vara-sportgrenar/start-speedway/resultat-speedway/resultat-bauhausligan-speedway

(Go to aktuella snitt)

And the sweeds are very clever people. So maybe that is the way

[Cast1rn]

.

Edited July 5, 2023 by Cast1rn

[Humphrey Appleby]

On 6/25/2023 at 4:18 PM, arnieg said:

Firstly the CMA is 4 as the point of the calculation is to normalise for the number of rides taken, and secondly if you are going to suggest I am mathematically challenged you really should be aware that I have a degree in Maths.

I'm guessing that averages are normalised to 4 rides as historically that was the number of rides each rider was programmed for (with some exceptions for reserves etc...). Therefore it could be easily understood by the layman as the average contribution a rider made to every match. Even with the later advent of tactical subs and rider replacement, it still makes sense as those are occasional rides that don't happen every meeting. 

Then nominated heats came along (although I think they were used by some heat formats in the distant past) which distorts the calculation as not only are some riders contributing more actual points on a regular basis, but the nominated ride will generally be harder as it usually involves the best riders of the night. Indeed, I think the averages of the top riders dropped after the nominated heat was introduced on a regular basis in 1988, although that also coincided with fixed gate positions which would also be a reason.

I suppose you could add a factor to points scored in the nominated heat to reflect the tougher ride, just as you could add a reducing factor to the reserves race for example to reflect the fact it's a 'easier' ride. But then it further removes the resultant CMA even further from the actual reality of how many points a rider is scoring. 

In the modern world, I do think it would make more sense to base averages on points-per-ride, but I guess CMAs are traditional and everyone knows the difference between a 10 point rider, 6 point rider, and 3 points rider etc... It would just end-up confusing everyone. 

Getting back to rolling averages, I think they're complete nonsense although I understand the reasoning which was to remove the early season distortion/potential manipulation when riders have only taken a handful of rides when being issued with a new CMA. However, taking the last x number of meetings really bears little relation to a rider's performance during a whole season, and even more so when the rolling period spans more than one season.

A factored CMA would be a better approach where a rider's average at the start of the season (or assessed average) forms part of the CMA, but becomes less of a component as the season progresses. By the end of the season, their CMA would (likely) be their actual average for the season and would also be their starting average for the following season. This way the CMA would always be based on a season's worth of data.