id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc
165,"Distance points ""feature"" in GAP... scoring modules",Stein Tore Erdal,Stein Tore Erdal,"Q. raised by Yoshiki:
""... question regarding scoring points. Please see the attched file (http://fs.fai.org/raw-attachment/ticket/165/task_result-Jname-stopoutland_2009-03-21_(20090321-2324).html). You can see the distance points of pilot id 8 and 57.
Their distances are same (40.4km) but the distance points are different, 924.3 and 921.4. 2.9 points difference.
Is the reason that the distance is rounded up?""
A ""feature"" ;-)
The distance score for a pilot comes from two things:
1. a linear factor: distance_points_linear = dist / 2.0 / best_dist
""dist"" here is the actual distance the pilot flew (not rounded).
2. a distance difficulty factor: The distance difficulty array is created by looking at the distribution of distances along the course.
A distance difficulty factor is created for each 100m of the task.
To find the correct factor for a pilot the distance he flew is rounded down to nearest 100m.
For ex. (in you case),
{{{
Avaliable distance points: 982.5
Best distance flown was 42.937
Distance difficulty array:
40.3km: 0.467836257309941
40.4km: 0,470175438596491
Pilot 57: flew 40.358km
-> 982.5 * (40.358/2/42.937 + 0.467836257309941) = 921.4
Pilot 15: flew 40.390km
-> 982.5 * (40.390/2/42.937 + 0.467836257309941) = 921.8
Pilot 8: flew 40.413km
-> 982.5 * (40.413/2/42.937 + 0.470175438596491) = 924.3
}}}
Pilot 57 and 15 both end up with the same difficulty factor but get differenct linear factor, hence different distance score.
All three pilots is shown in the result-list with 40.4km since the result stylesheet (task_result.tkr.xsl) rounds the distance to nearest 100m.
It might be more correct to round the distance down the nearest 100m before calculating the linear factor.
Any opinions?
Stein-Tore",task,closed,minor,1.2.13,Other,,fixed,GAP scoring,