LetsRun.com Reader Figures Out Median/Mean 5k Times For LRC Message Board Visitors

By LetsRun.com
October 21, 2009

You may have noticed this thread on our website this week: My 5K PR is 15:45. Am I the median for Letsrun? Well, if you didn't notice it, one of our amazing readers did. And as you can read in his email below, he was willing to do a stastical analysis of the responses on the thread.

The reader didn't want attribution, instead he wanted readers to know he's "just a fan of the sport (and of LRC) whose job involves a large amount of data analysis. It was a welcome diversion to work on this for a change." His letter reads:

Brojos:

Attached is a graph I made of the distribution of 5k PRs of posters on
LRC as taken from the "I run 15:45 for 5k. Am I the median for
Letsrun?" thread. The data is current as of 3:00 PM EST on Wednesday.
The median (15:40.5) ended up very close to 15:45, though as many
posters noted, there will be an inherent response bias because slower
posters may be less likely to read and/or respond to the thread. It is
however interesting to note that the distribution is approximately
normally distributed, with a mean of just under 16 minutes.The mean is
higher than the median because of the slower outliers to the right of
the graph, and when these are removed, the mean very nearly
approximates the median of the distribution.

I'm a big fan of the site, and keep up the good work.

Figure 1. 5k times of LRC posters as of 3:00pm Wednesday October 21, 2009.