(Update: Click here for a look at the numbers from races through mid-August)
The other day, @jamieofthenorth tweeted about how tough this year’s Boston Marathon was because of the heat. “At the 2011 #bostonmarathon, 10,374 runners requalified for Boston. This year? Just 2705.”
That got me thinking. It was a tough day, that’s for sure, but you also have to remember to take the new, faster, qualifying times for 2013 into account when comparing qualifiers for Boston in 2013 with qualifiers for 2012 .
@jamieofthenorth got his numbers from MarathonGuide.com, so I went there to poke around. Their lists show the marathons with the highest percentage of qualifiers and the races with the most qualifiers. It’s only April, so a lot of races that were on the 2011 lists have not been run yet this year.
If you compare the qualifying rate in 2011 (for 2012) with the qualifying rate in 2012 (for 2013) for the seven races that show up in both years, you get this:
| Race | 2011 % | 2012 % | 2011 temp | 2012 temp |
| Houston | 8.3% | 13.1% | 67 | 70 |
| City of L.A. | 4.1% | 3.6% | 56 | 58 |
| Disney | 4.7% | 3.6% | 64 | 77 |
| RnR Arizona | 13.9% | 7.4% | 71 | 63 |
| Miami | 10.1% | 6.7% | 74 | 76 |
| National | 14.6% | 4.9% | 47 | 75 |
| Boston | 43.6% | 13.1% | 61 | 87 |
The percentage of runners who qualified for Boston at the Houston Marathon actually went up, but I figure that anomaly might be due to the quality of the extra runners (about 10% more than 2011) who showed up because the U.S. Olympic Trials were held there the day before.
The qualifying rate at the National Marathon in DC plummeted by two-thirds. That’s about the same drop as Boston but, like Boston, it was much hotter in DC in 2012 than it was in 2011.
In the other four races, the qualifying rate dropped on average by about a third. That sample is only from a few months, but it covers well over 40,000 runners, so for now I’ll assume that that’s the approximate size of the effect created by the new BQ times.
It’ll be interesting to look back in December to see whether those numbers hold up over the course of the year.
Y42K blog has moved to Y42K.com 
[…] Some interesting data-crunching from Ray Charbonneau, who blogs at Y42K?: If you compare the 2011 and 2012 fields of some major marathons, you'll find the Boston qualifying rate on average has dropped by about a third. […]
Great stuff. More important: What was the BQ rate at last fall’s big marathons, where a lot of runners would have been attempting Boston qualifiers. Amby Burfoot, Runner’s World
Amby, It appears that MarathonGuide calculated potential qualifiers from the 2011 races using the 2012 BQ standards, not 2013, even when the race was a 2013 qualifier. I’m trying to work with them to sort that out.
The Houston temps look off to me. 2011 was very warm and humid, even before the gun. It was cooler and much dryer in 2012 and didn’t start to get warm until later in the race. So, the better results in 2012 are consistent with my experience of the conditions.
All temps listed above are the local high for that day. While the weather in Houston may have been better in 2012 than in 2011, I suspect that it wasn’t enough better to counteract the typical BQ rate drop all by itself. I don’t KNOW that, of course. I do know that a lot of my fast friends went to Houston only because of the Trials :-).
I ran a BQ time in the RnR AZ race this year and marathonguide.com does not reflect this. My time would qualify for both 2011 and 2012. Be careful, the data may not be correct and assumptions may be made on bad data
Thanks, Jim (who ran AZ in 3:22 at age 46). If MarathonGuide gets back to me, this is something else to ask them.
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I found this really interesting, but I am wondering if you have had a chance to update over the last few months. I ran a BQ under the new qualifying standards, but only by a minute……I wonder if that will be enough.
Check back tomorrow…
[…] Here are the numbers (for a look at my methodology, refer to my blog post from April): […]
Updated numbers through mid-August are here:
[…] from the cities and towns along the marathon route, will have some tough choices to make. I have a history of obsessing (there’s a reason one of my books is called Overthinking the Marathon) […]