Statistical Skier

Therese Johaug already made me write one post on this topic this championships and now she’s forced me to write another. So I promise I’ll keep this short, unlike the gaps from Johaug to the next skier.

Therese Johaug once again won a race by a very large margin, this time in the 30km classic mass start in the 2021 Oberstdorf WSCs. Personally, I don’t think that I’m as impressed by huge mass start winning margins as other people seem to be. Obviously, unlike interval start races the visual impact of large gaps in mass starts can make quite an impression. But for me, at least, the relationship between my amazement and the size of the gap is not strictly linear. It’s probably something more like this:

When a skier pulls away in a mass start race, I do become steadily more amazed as the gap grows, up until it reaches a certain point and then my amazement sort of plateaus, and even declines a bit after a while. (Obviously, the specific units on the x-axis of this Very Serious and Rigorous graph would change for races of different lengths.)

Which is all just to say that I found Johaug skiing away from the field extremely amazing, up until the gap started getting up into the 90 second territory. After that, I’m not sure any further increases in the margin mean all that much. But that’s just me! You can obviously take joy and amazement from whatever you like.

A consequence of this is that I don’t think you can meaningfully compare winning margins from mass starts except at the level of breaking it down to basically three categories:

• It was a sprint finish
• They were in contact but not enough for a sprint
• There was a very big gap, it wasn’t close at all

For me, mass start winning margins fall into one of those three categories, and I personally don’t get much out of any further parsing of the time gap. But what would I even be here for if I didn’t give you a list? So here’s a list of the biggest (by percent back) winning margins in major international events in the last 30 years or so.

So perusing this table you can see why Johaug’s 10km freestyle interval start gap is still the most impressive thing I’ve seen recently.