Marathon pacers matter (Seattle Marathon 2007 to 2011)

Update 12/3/2011: Unfortunately, the information below can’t quite be trusted. I’ve taken a closer look at the results I pulled from the Seattle Marathon site at the time and the results today and I can definitely say that the data I pulled was not official and the results today are also incomplete. I’ll need to make an update to this post and all this research some time when official, complete results are available. What’s wrong? In the data I initially pulled, I see things like women’s winner, Trisha Steidl’s splits as 1:10:29 for the first half and 1:34:09 for the second half for a 3:03:38 (which is wrong and doesn’t add to that final chip time) – today the results say 1:29:32 and 1:34:09 (which seems right). This suggests today’s results are closer, however today the pacer chips are missing from the results. Anyway – I’ll work on this again when I can…

I’ve started collecting the data from the Seattle Marathon, 2007 to present and am doing some analysis on it, specifically from the perspective of the marathon pacers since I organized the pacers this year and we just finished the race. If I find the time to keep analyzing the data, this will probably be the first of many posts on the subject. If I don’t, this might be the first of one.

Assuming I’ll keep writing on this – here are the methods I’m using for the data source…

  1. I pulled down all full and half, male and female results from 2007-2011 and dumped the data into Excel.  This represents over 45,000 finishers over that period between the races.
  2. I did a little data cleansing – many records contained no data for the first split and just turned these into 0’s for processing in an Excel PivotTable.
  3. I used an Excel 5 minute rounding function to approximate the pacer that some finisher would be behind (e.g. a full finisher crossing the finish line at 4:13:35 evaluates to a 4:15 pacer, a full participant crossing the midway point at 2:02:41 would be behind the 4:10 full pacer, and so on).

Through 2010, the Seattle Marathon only offered full pacers for 3:30, 3:45, 4:00, and 4:45 (unhappy with this, in 2010 I lobbied for us to add 3:10 and paced that myself).  In 2011 I organized the pacing and changed the pacer structure to offer more times3:00, 3:10, 3:15, 3:20, 3:30, 3:40, 3:45, 4:00, 4:15, 4:30, and 4:45).

When trying to process this in the past, I had frequently tried to look at the finish result. This is pretty impossible to make any conclusions off of because (if you hadn’t heard) a marathon is hard and there are all sorts of reasons people do or do not make their results.  While it’s a lot more important to ultimately answer “did people make their goals?” without a questionnaire that’s fairly impossible to tell.  It *is* pretty easy to tell from the first half split, though, where people were setting their goals, and looking at some of that data, I see a clear indication that the pacers and pace groups matter.

The following chart shows a plot of full finishers over these 5 years of races and highlights the pacers that were offered for the races in those years.  The data shown is based on what 5 minute group they were running with at the first half split (not the finish) and the red rings highlight the 5 minute segments for which we had a pacer.

  • 2007-2010 there was some pretty clear clustering in most years of a large group clustered around the pacer segments. Sometimes the spike is a little outside the circled block, but I believe there is some pretty clear visual correlation (this includes 2010 when I had a group on track for 3:10 at the half)
  • 2007-2010 looking at the distribution of the field outside the pace groups shows a fairly smooth distribution of finishers. I think this further suggests that when there isn’t a pacer to associate with, runners tend to just distribute themselves more evenly.
  • In 2011, the distribution is much more choppy with more clusters of runners in the race with most clusters inside a pace group and most of the rarefied sections outside the pace groups.

This doesn’t help understand whether people are achieving tougher goals and there is no sophisticated analysis in here at all (maybe I’ll get to some of that in a later post) but I believe that it definitely indicates that runners will choose to run with a pace group if one is offered in the race.

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