If a bunch of different caps were being tested, with the goal of figuring out which one is better AND why, then knowing the weight of each cap would be important (as would knowing the material composition, thickness of the material, etc). But if you are just trying to figure out if a cap is better than no cap, then you just test both groups to see if there are different forces and/or rates of concussion - the weight is not going to help answer any of those questions.But you just said the weight matters. Weight is weight. Unless they're playing football in space, it's part of the whole equation.