Yes (except for Alex's personal data).



Actually, we do (have some idea):

1) Alex is a coach who has access to power data from his clients, and

2) he stated (paraphrasing) "here's some data from a group of riders of mixed abilities targeting track endurance events".

So, while we don't know how the data were collected, logic dictates that it is (largely) cross-sectional in nature.



Aye, but that wasn't the data that yielded the R^2 to which Steve referred.