Importantly , however , after statistically adjusting for the strongly confounding influence of the year in which riders competed , in both studies the speed differences between riders disappeared .
The rider main effects explained trivial amounts of 0.1-1.3 % of the variation in riders ' achievements .
Importantly , however , after statistically adjusting for the strongly confounding influence of the year in which riders competed , in both studies the speed differences between riders disappeared and the rider main effects explained trivial amounts of 0.1-1.3 % of the variation in riders ' achievements .