Sounds like a classic case of Simpson's paradox [1]. Here's how it could work, but I've made everything up so might not be true at all - it's just an example of

Sounds like a classic case of Simpson's paradox [1]. Here's how it could work, but I've made everything up so might not be true at all - it's just an example of how those numbers could exist: * KSI goes up far less than expected as the journey length goes up (less than linearly, and maybe even down slightly between some categories). That's because the longer journeys are made by much more experienced cyclists - by definition, a very unfit cyclist never cycles 25miles, for example. * But the category of very shortest journeys makes up by far the largest proportion of journeys, so a straight unweighted averages of KSI across journey length categories would give a very unrepresentative view. * Those women that do cycle tend to be in the lower journey length categories because on average, women are less physically fit. In other words, women would tend to be in the relatively more dangerous category of shorter journey length. It's not more dangerous because it's shorter - it's more dangerous because you had to be less fit to be in it in the first place. Again, note that the above is all made up. But it shows how you could get to the contrdictory-sounding stats of the parent comment. [1] https://en.wikipedia.org/wiki/Simpson%27s_paradox https://en.wikipedia.org/wiki/Simpson%27s_paradox