Marit Bjoergen’s Best Freestyle Race

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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US Biathlon Preview: Men

My previews for the US biathlon teams will be briefer, which reflects the fact that I know less about the US biathlon team, and biathlon in general.  Feel free to correct me in the comments if I get anything horribly wrong.  For example, I’m going to take a very simplistic approach to who’s actually on the US team by just looking at the skiers I have data on.  The team selections seem pretty fluid to me through and between seasons.

Let’s start with the men.  I’m going to begin with the men who did World Cup or Olympic races last season:

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Kuusamo WC Recap: North Americans

As always, there’s lots of stuff I could focus on, but we can’t have everything.  As is usually the case, the weekend was a bit of a mixed bag for the North Americans.  Kris Freeman continued to look quite strong despite some bad luck with his poles.  Alex Harvey and Devon Kershaw had much stronger weekends this time around.  Kikkan Randall had more solid distance races, although her sprint race wasn’t stellar.  And so on.

Let’s start out with the same style graph I used in my earlier post, only this time highlighting the North Americans:

While I haven’t labeled the athletes individually, it should be pretty clear who’s who.  Harvey clearly was having a great weekend but couldn’t hold on in the skate race yesterday.  Kershaw and Freeman did well despite pretty pedestrian sprint races.  As for Randall, if she had had an ok (for her) sprint race, that could easily have bought her 20 seconds, and with a great sprint race (if we kept the distance results the same, which isn’t really realistic) she could have contested for a place in the top five.

I need to comment  a bit more on Stephen and Arritola, since I disagree somewhat with the characterization of their freestyle races in this FasterSkier recap.  As a commenter on that article correctly points out, much of the gains in overall place they made were the result of other skiers DNF/DNS-ing (at least half, or a bit more).  I’m sure this will spark some measure of debate, but I have to agree with the original commenter.

Let’s start with the graph above.  We’re plotting seconds from the median skier after each stage, so in the case of Arritola, she lost time yesterday on the median woman, not just the leaders.  Stephen held about even relative to the median woman.  If we isolate just their skate performances yesterday in terms of FIS points compared to their other WC starts we get the following: Read more

Kuusamo WC Recap

This recap of this past weekend’s WC races will be a little different than before.  Rather than focus on individual performances, I’d like to look at the races as a group.  Stage race formats are relatively new to the cross country world, and these short stage races are even newer.  Since they are roughly modeled off of cycling style stage races, I thought it might be interesting to graph them accordingly.

Over the summer, I had some fun making bumps charts for the Tour de France and the Vuelta a España.  What do we get if we make the same plots for XC stage races?

Each line represents a single skier.  I calculated the cumulative times for each skier after each stage (including the time bonuses for the sprint race) and then plotted each skier’s difference from the median after the end of each stage.  In a cycling race, the median time would roughly represent the ‘peloton’.  Lines that dip downward mean that athlete gained time; lines the shoot up are athletes losing time.  Lines that end before the last stage are skiers who abandoned.

We can easily spot Marit Bjoergen dominating everyone in the women’s race.  The men’s field saw a lot more shuffling, it seems.  The peculiar effects of pursuit style starts are apparent as well.  Despite the final stage meriting it’s own WC and FIS points you can see many skiers who were well off the back at the start of the freestyle stage losing even more gobs of time.  When you’re off the back in a ‘mass start’ type race, people have a tendency to just let up a bit and stop racing, I imagine.  Some of these folks may have just had a rough day, of course.

You can also see some distinct clumping in the men’s race.  You had a fairly large train of leaders, with a few individuals separating themselves by the end of the freestyle race and then two groups further back with a handful of skiers left in “no man’s land” between the first and second groups.

For the women, the front of the field ended up fairly spread out, but towards the middle you start to see some small groups of skiers together.

One of my main interests in making these plots was to investigate the relative importance of each stage to the overall results.  I have suspected for some time that performing well in the sprint races isn’t quite as crucial as doing well in the distance races.  It’s hard to see in the version above, but let’s try highlighting the skiers who didn’t qualify for the elimination rounds in the sprint: Read more

Race Snapshots: Kuusamo 10/15km Freestyle

Use some caution interpreting these, due to the unusual race circumstances today.  These graphs apply only to today’s freestyle portion of the Kuusamo races, and each skier’s percent back (and hence their FIS points) can be influenced by the race tactics on the course, since we were dealing with a pursuit-style start and people were largely jockeying for position in the overall classification I think.

For example, skiers with no one near them (front or back) may have little incentive to push hard, so they’re results here may look bad.

This is a curious race format, since as far as I can tell FIS awarded WC points (and separate FIS points) for the results of just today’s freestyle portion, as well as the overall results of all three days.  (What the FIS points mean for the combined results, I’m not sure.  It includes a sprint qualifier!)  So technically, everyone ought to have had plenty of motivation to push hard regardless of their position on the course today, but human psychology is a funny thing.

Anyway, just wanted to warn you.

As usual, the (very large) full versions are below the fold, and you need to click on them for the full size.

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Race Snapshots: Kuusamo Classic 5/10km

Another decent day for Kris Freeman and Kikkan Randall it seems:

Full version below the fold (click on them to see the full size image):

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Week In Review: Friday Nov 26th

Happy Thanksgiving!  The racing season is off and running:

Race snapshots will continue through the weekend with each WC race.  Things to look forward to next week:

  • Previews of the US biathlon team, along with race snapshot graphs for the kickoff of the biathlon WC season.
  • Recaps of the Kuusamo WC races and also perhaps the West Yellowstone SuperTour races.
  • If you thought that SkiTrax and Fasterskier could post a press release talking about a compartment syndrome survey, in which they use a bunch of fancy-shmancy statistical language like “p-values” and that I wouldn’t comment on it, well, you clearly don’t know me very well.  I have a lot to say about that survey.

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