Statistical Skier

Last week I ranted a bit about the inadequacies of F-factors[1. The scaling factor FIS uses to adjust FIS points depending on whether the race was an interval or mass start.].  We looked at the results from interval vs. mass start races and determined that they do indeed produce different distributions of percent back’s (PB’s).  Specifically, the results of a mass start race are more likely to be bunched closely near the top, meaning the top skiers are more likely to finish closer to the winner.  This leads to many more low FIS points than you’d see in a typical interval start race.  Here’s the graph from that post summarizing these different distributions:Recall that FIS’s F-factor solution to this problem is to scale all mass start points up by a factor of 1.75, effectively expanding the blue curves above to the right.  This resulted in the following distributions:We noted that nothing really has been solved here.  There is still a huge difference in the points assigned between interval and mass start races. Continue reading ›

Last week I looked at the distance race results of some skiers who had been caught using performance enhancing drugs.  A commenter wondered if I could show some data for “suspected dopers” as well.

Honestly, I was a bit reluctant to do that.  I mean, as much as I hate doping, the negative consequences of being labelled one are enough that I think we should be pretty careful about throwing accusations around, particularly in public.

In the end, though, I think we can do this responsibly by being very careful to remember that the only certain way to catch dopers is in the act (and even then it can get ambiguous).  I sort of hope that this exercise will reinforce the lesson from my last doping post that looking for evidence of funny business using graphs of race results is highly unreliable.

Continue reading ›

I just finished reading a great article checking in with US biathlete Tim Burke as he gears up again for next season.  I was vaguely aware that Burke had a great season last year but a disappointing Olympics, but I don’t follow biathlon as closely as cross country.  So I thought I’d check some data and educate myself a bit. Continue reading ›