Another 24 Hour Lap Time Post!

I'm still working on getting the full lap data for Great Glen, because I'm sure there's a lot of cool stuff in there.  In the meanwhile, someone sent me this email that was too well done not to post (with his permission, of course), which answered some of the "but what's the statistical certainty???" questions that were posed in the comments last week.  Enjoy.

"Hi Colin,
Don’t know if you remember me.  I’m [explanation of how we know each other redacted].  Anyways, I enjoyed your cheater writeup.  You’re probably done with comments about this whole deal, but I was bored at work this morning and took a look at some of the lap data.  Some of the comments were asking about statistical certainty of Sam Anderson’s night lap times being fake.  The short answer is “oh my god, yes”.

I looked at the lap times from the top 10 teams from the 2011 24hogg.  I discarded the first lap (running) and then averaged every rider’s laps started before 8 pm and called those day laps, and averaged every rider’s laps started between8 pm and 5 am and called those night laps.  So from the top 10 teams, we have a population of 32 riders, and I added Sam Anderson’s laps to the data set.  When you plot them, you get this graph:



The dashed blue line represents even lap times day and night.  As you would expect, every legit racer is, on average, at least 2 minutes slower in the dark.   If you look at the ratio of night:day for the 32 riders, you find with 99.9% confidence that all riders should run lap times 1.078 to 1.147 times slower at night compared to day.  And this makes intuitive sense as a good rider running 40 minute day laps and going 8% slower at night would run 43 minute laps.

So onto Sam’s night:day ratio of 0.998.  If you run a t-test to determine if his lap ratio is significantly different from a normal person's, you find that there is 99.999999999% confidence that his is an outlier.  This translates to a 1 in 1.3 million shot of his lap times happening without some outside influence (cheating, mechanicals, whatever).  

You made a great case that something fishy was going on with his lap times.  Just though you should know statistics is on your side.




Graham"

Comments

Sean Yeager said…
Graph image doesn't appear to work...
Colin R said…
Fixed now... I think?
Anonymous said…
"This translates to a 1 in 1.3 million shot of his lap times happening without some outside influence (cheating, mechanicals, whatever)."

So you're tellin' me there's a chance. YEAH!

https://www.youtube.com/watch?v=KX5jNnDMfxA
Bemery said…
This comment has been removed by the author.
Anonymous said…
Where are Sam Anderson's laps plotted on this graph? After initial glance, I don't see any lap slower during the day than at night, but could be over looking something
Colin R said…
"The dashed blue line represents even lap times day and night. "

Sam is the circle on the dotted line at about y=40 and x=40, aka the only person in the data who rides as fast at night as they do during the day.
Russ Campbell said…
Last nail -> coffin?
Michele said…
Russ, your optimism is one of your most endearing qualities.
Colin R said…
This isn't a nail in the coffin so much as the last shovelful of dirt on the coffin.
nate c said…
this chart is wrong ebcause the x axis and y axis are flipped they should be the other direction so the x should be the y and the y should be the x so sam didn't cheat
Bemery said…
Couldn't it be a decent strategy, to hold back a bit until night falls? With the RealTime scoring (which is totally awesome), I could see it being a worthwhile strategy to get the competition to ease off a little bit, and then take them by surprise by going all out for the first time later on.
Colin R said…
Bremery:

I think that's unlikely to be an effective strategy, because it basically hinges on it coming down to a 2-team race, and the leading team deciding to do double laps because they think their cushion is secure. Since a full rotation of double laps costs about 24 minutes (+3 minute per lap for 8 laps), your team would have to be significantly off the pace (30 minutes or more?) by midnight to get the leading team to adopt this strategy, which is a pretty big gap to close once you show your true strength.

...and if the leading team doesn't fall for it (maybe because one of the other 50+ teams at the event are challenging them) then you've effectively just handicapped yourself by riding some laps at less than full gas.

In my experience, with 2 hours of recovery between laps, you can basically ride every lap full gas, and "going easy" for a lap doesn't cause the following lap to be much faster. So it's really hard to "store energy" for later -- at least in my opinion.
24 HOGG racer said…
Bemery (Ben Emery, I assume): You went out for a lap at 7:50am, clocking in a respectable 56 minutes. Did Sam pass you on this lap? If so, where? Just curious. I don't know if this will prove anything but if there's any exonerating evidence it would be good to get it out there.
24 HOGG racer said…
Sorry, your lap actually started at 7:36, Sam's started at 7:50 (Sunday morning)
Dave Warner said…
Are there any preliminary T-shirt designs for this yet?

I'd be interested in a pre-order.
Anonymous said…
I know the bridge was new last year but when they close it at night the reroute adds time. I'm not sure how much. Maybe 1 min? So that alone would make a fastest lap even harder.
Anonymous said…
A better visualization to show the outlier would be a histogram of night:day ratios. With correct bin widths it would be more intuitive to the layperson than this plot (not to knock it in any way...it's appreciated).
Bemery said…
I don't remember much about that lap except for how much a regretted not eating breakfast beforehand. I was very gassed but someone definitely passed me, possibly two people on the dirt road before the Wilding loop. I think near the beginning of the "Strava Climb". I didn't catch who my passer(s) were but they were definitely there and gone very quickly.
Anonymous said…
Ever one keeps talking about night laps but you guys keep missing the point that Sam never truly did a night lap he did four lap in all 1st at 12:00 noon, 2nd at 4:12pm, 3rd 5:12am and 4th at 7:50.
Colin R said…
He did a bunch of night laps in 2010 and 2011 that had completely unbelievable splits, that's why this post is talking about night laps.

If you think there is no correlation between cheating in 2011 and cheating in 2014 then you are correct that this is not about night laps.
Anonymous said…
Know I believe he cheated I was just pointing it out about the night laps
24 HOGG racer said…
Bemery- I think we've all been there, either "I should have eaten" or "why did I eat that?"

If someone passed you before the Wilding loop it wouldn't have been Sam, as he started about 14 minutes after you (unless you stopped and waited at the start you would have been on the loop already when Sam was just leaving the tent.) It seems odd then that you wouldn't remember your friend passing you later on that lap. I know I make a point to at least say hi to anyone I know on the trail, and you'd think that Sam would call you out by name when passing you. Like many of the arguments people have employed to defend Sam it completely defies belief. I'd say there is no way you wouldn't recognize your friend passing you.

Sorry man, it sucks when your friends do crappy things, but I think it's time to stop making excuses for Sam. He's probably feeling pretty bad right now and could use the support of his friends. I'd say it's up to the people who actually know him to convince him to admit he cheated and apologize.

Popular posts from this blog

Should You Throw Your Water Bottle When Racing a Road Bike?

Greenfield Criterium HYPE POST

Midnight Ride of Cyclocross Race Report