The "2025 Chicago Marathon" was an absolute blast! 53,000 people from around the world competed in one of the fastest courses in the world! I completed it in a graceful 2 hours and 48 minutes, with splitting halves of 1:20 and 1:28, the latter half stopped by the infamous wall! Featured Instragam pic and Strava embed below.

Data Analysis - Distribution

With Python and the requests module - we scraped the entire sets of results. GitHub repo with the code located here.

First - the entire dataset including all male and female runners:

Next - only the males:

Finally the females whose distribution appears more symmetric than the males. Another observation is that while the mean, min and max are reasonably different (measures of location) - the measure of spread in the standard deviation is almost identical:

Data Analysis - Marathon Splitting

Some marathoners attribute their run as a "positive split" or "negative split". If the first half of the marathon was faster than the second - then the run is a positive split. Else, it is a negative split. Intuitively - a marathon is so long that one would expect the second half to be slower than the first. If a runner does the opposite then there is a clear strategy to conserve energy and finish strong. Here we investigate the success of this strategy among males. Define $$S = \text{Second Half Marathon Time}-\text{First Half Marathon Time}.$$Then if $S$ is positive - the second half of the marathon was longer than the first. Below is a histogram of $S$. An expected result, though, illustrates that a negative split is not common, making up about 10% of all cases.

Next we investigate the linear association between $S$ and marathon finishing time. A scatterplot and the regression results below. There appears to be a positive correlation between spread and marathon finishing time, implying, the smaller the spread (in the $\mathbb{R}$ space) the smaller the finishing time! Therefore, the best runners are those who are bringing $S$ down. What we can also see is that the best runners are solving for $ -5 \leq S \leq +5$.

Looking forward to the next marathon!