Statistical Skier

Another cold, cold day in Östersund today, but a great one for Finland’s Kaisa Mäkäräinen and Germany’s Miriam Gössner.  Full version below the fold.

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Who impressed me most in the races last weekend in Kuusamo?  Well, I have to agree with one of my commenters in picking Germany’s Nicole Fessel.  I’m not crazy enough to stay up till 1am to watch the races live on the internet, so I only have the results to go by.  Still, how impressive has her season been so far?  Let’s take a look:

WC, WSC and OWG results for Nicole Fessel.

Note I’ve plotted the finishing rank here, so as to put sprint and distance results together.  Her distance results have, um, improved.

I might be reading way too much into her sprint results, but does anyone else see the two diverging trends after 2007?  One going up and one going down? Unless someone has a really plausible explanation for that I’m going to chalk it up to random chance (the human eye likes to see patterns, even if none are there).

Let’s put her distance results trend in a little more context by plotting all of them, using FIS points this time:

Nicole Fessel's distance results.

You just don’t see athlete development patterns like that every day.  Promising early career, followed by some struggles between 2006-08, followed by rapid improvement.  How will she race for the rest of this season?  Anyone care to weigh in?

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Can’t leave out the poor biathletes, now can we?  Biathlon doesn’t have a point system like FIS points, so these will all be using raw percent back.  If you’re familiar with these sorts of measures, you’ll notice that percent backs in biathlon are frequently quite a bit higher.

For a variety of reasons, it’s harder for me to stay on top of women’s name changes due to marriage with the biathlon crowd.  If you spot a mistake (i.e. a skier who’s name has recently changed and my graph seems to show that they have done almost no previous races), let me know.

I struggled with how to incorporate the athlete’s shooting results from that day into the graph.  I tried all sorts of visual elements that just didn’t work well.  So I opted for the very simple route of putting the total number of misses right on the graph, over to the right.  Not very elegant, maybe, but simple and easy to understand.  As always, reduced version first (top 30 plus North Americans) and the full version is below the fold.

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Marit Bjørgen commented somewhere that her win at the WC opener in Gällivare, SWE was “the best skate race of her life”.  Sadly, I can’t find where I read that, otherwise I’d have a link for you.  Obviously, I found that kind of intriguing.  Let’s look at Bjørgen’s race in a bit more detail:

This is the difference in percent back between Bjørgen and the top thirty women at Gällivare in all skate races where they’ve competed against each other.  (Since there’s quite a bit of data on Bjørgen I was able to be a bit more picky and only include skiers she’s raced against at least 5 times.)  The red line indicates the median percent back difference for each season.

This isn’t a direct comparison to specific races, of course, so this doesn’t tell us directly whether this particular race (in the blue) is better than any of her past skating efforts, but it provides some useful context.  The most obvious thing to note is that the seasons with the most similar looking performances are from 2004-05 and 2005-06, where Bjørgen appears to have never lost a major freestyle race against these particular skiers (all the dots are below zero).  Additionally, the median percent back difference from Gällivare is quite a bit below the median from any other season.

A little editorial comment here.  Statisticians tend to react to extreme events differently than other people.  The typical response is to assume that this sort of thing is going to keep happening, whereas statisticians will tend to assume it was a rare event, unlikely to happen again.  In this case when Bjørgen opens the season by absolutely crushing the field, there’s a natural tendency to begin to expect Bjørgen to destroy the field like this all season long (or at least to seriously suspect this is going to happen).  My reaction was more along the lines of “There’s no way she can sustain that level of dominance for any length of time.”

Now, Bjørgen may well continue to win races, perhaps most of them.  But I doubt we’re going to see her rack up margins of victory above 2.5% on a regular basis.  Unless, of course, she does, in which case I’ll eat my words.

But how about a more direct, simple comparison?   How did that victory compare to Marit’s other WC/OWG/WSC wins?

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