Week In Review: Friday Apr 22nd

I took a break today from the retiring skier posts, but they will resume next Friday…

  • The first two parts of a brief season review for the North American skiers this week, focusing on the men’s and women’s distance skiers.
  • I did a little exploration of how we might put together some data on (very rough) FIS point benchmarks for developing skiers, based on a post by Pete Vordenberg here.

Week In Review: Friday Apr 15th

What a taxing week I’ve had…

Ha ha. Very funny. (It’s tax day in the US, for you foreign readers.) Thanks once again to Skaði Nordic for sponsoring this week in review:

  • A two part series examining the question of ‘home snow advantage’. The short answer is that while overall there is generally no (statistically) significant effect, there are noticeable differences between athletes and nations that are quite interesting.
  • A look back at the career of a great Italian sprinter who’s retiring this season, including some interesting stats that place her as one of the most consistent sprinters ever.

Week In Review: Friday Apr 8th

Gee, I wonder what the big news in XC skiing this week could be? It sounds from the translated reports from Norway and Estonia that I’ve read that Andrus Veerpalu tested positive (both A and B samples) for human growth hormone, but is denying any wrongdoing. Naturally, this means I started the week off with:

  • A new post revisiting my older one on Veerpalu. A common accusation against Veerpalu (and other suspected dopers) is that they have an unusual ability to show up at major events and ski much faster than they “normally” do. What I hope people take away from these two posts is that (a) our intuitive sense for “unusual” results does not always match the data, and (b) the answer you get will depend strongly on how you measure performance. The resulting situation is pretty ambiguous, which is why I would never recommend this line of reasoning as a serious accusation against someone.
  • A look at what we can learn about pacing from split times.
  • The first of several posts looking back at the careers of skiers who have decided to retire. This week was Pirjo Muranen’s turn.

Finally, I’m going to take this opportunity expand briefly on something I tweeted about. I read that one of the statements made at Veerpalu’s press conference in his defense was that he had passed more than 100 drug tests in the past. Although sports fans are becoming more educated about the statistics of drug testing, some confusion still remains. Without getting into the technical details, here’s the basic story.

Drug tests can make two types of mistakes: false positives, where we incorrectly label a clean athlete as a doper, and false negatives, where we incorrectly label a doped athlete as clean. In general, any testing scheme will involve a trade-off between these two types of errors. If you tweak your methodology in order to reduce the number of false positives, you will inevitably increase the number of false negatives. This trade-off cannot be outwitted! I often hear people suggest that maybe if we combine two, or three tests, or engage in some other complicated scheme, that you can reduce both types of error at the same time. Some testing procedures will be better than others in terms of both types of error, but whatever complicated combination of procedures and tests you invent, the end result will always amount to a single, big test that is itself subject to this very trade-off.

Drug testing in sports, for obvious reasons, is often calibrated in a such a way that false positives are considered far worse than false negatives. Specifically, tests are often constructed in order to be very careful to avoid falsely accusing an athlete of doping. Sadly, this means that negative results are simply less informative, in that they are much less likely to actually mean the person is clean.

My general conclusion as a stat guy is that I’m much more likely to believe that a single positive result is accurate than I am a single (or even many) negative results. A string of negative results doesn’t receive zero weight in my book, but they don’t receive much. (This is ignoring extra-statistical issues like mishandling samples at the lab, corrupt labs, or other similar human factors.)

Week In Review: Friday Apr 1st

No joke! Seriously, though, I thought about writing an April Fool’s post and then realized that I kind of hate April Fool’s posts. Probably because I’m an über-boring statistics geek who doesn’t know how to have fun at all. Or something. Winter’s ending elsewhere, though were I live it never really began. Spring here means I impatiently wait for the temps to start climbing above 60F, cause otherwise I won’t touch my road bike. Yeah, I’m a fair weather biker and proud of it. Of course, the fact that it’s rained pretty much every day this week hasn’t helped. Grrr.

Anyhoo, thanks again to Skaði Nordic for sponsoring this week’s Week In Review:

Week In Review: Friday Mar 25th

You may have noticed that things have slowed down a bit here lately, which is natural with the season drawing to a close. I’m going to back off a bit with the posts and try to keep to just a Mon-Wed-Fri schedule during the off-season as best as I can. Some things I’m planning on doing over the next few weeks include some obvious stuff like recapping the performance of the US/Canadian teams this season and looking back at the careers of some of the folks who are retiring. I have some other stuff up my sleeve as well, but if you have any ideas/questions for analysis about specific nations or athletes, don’t hesitate to drop me a line.

  • A short post on Leif Nordgren who had some very strong results this year for such a young American biathlete.
  • I also of course had to take a look at Finn Hägen Krogh, another youngster who finished the season off with a bang.
  • Finally, I gave a little taste of some of the split timing data I’ve managed to get my hands on this year, highlighting the differences between mass start and interval start races.

Week In Review: Friday Mar 18th

I’m on the road again for 50k number two of the season. Not looking forward to this one as much. The course doesn’t really excite me, and there are a ton of crazy fast runners here so it’ll be a miracle if the leaders haven’t flown home by the time I finish. Stupid fast people!

Anyhoo, the season’s almost done…

  • We had the Lahti XC World Cup races: the pursuits and the sprints, and some brief recaps, despite a few snafus with the live timing.
  • The World Biathlon Champs wrapped up with the mass start races.
  • I gave a very general assessment of how the US and Canadian teams fared at World Biathlon Championships compared to the past.
  • The final weekend of biathlon WC racing is under way starting with some sprints, and a recap in which I managed to put my foot in my mouth.
  • Now the XC World Cup Final mini-stage race thingy is going on, starting with a classic sprint (recap) and continuing with the prologue.

Week In Review: Friday Mar 11th

I managed to post a fair bit this week, though not today really, despite being out of town. Thanks again to Skaði Nordic for sponsoring Week In Review.

 

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