Some of the reported Chicago Marathon mile splits made no sense to us. Both Kelvin Kiptum and Sifan Haass ran ran super fast for mile 19 but super slow for mile 20? So we did a little investigation and found that for Kiptum's mile splits to be accurate, he'd have had to run sub-4 mile pace during both mile 19 and mile 22.
That didn't happen and Chicago agrees with us:
This isn't the first time we've done something like this: