Using the Alter Cup as your measuring stick for determining the effect of crew weight on performance may not be your best bet. While all crews are sailing the same boats, the boats are also set up identically. Adusting and tuning of the rig to maximize the boats performance for your weight and conditions is not permitted. ie....heavier crews were not permitted to power up their rigs in the light stuff and light crews were not allowed to depower their rigs in the heavier stuff.
You are thinking in the extremes. Sure, the boats are set up the same general range. Sure it is not optimized to the extreme for feathweight or monster teams but close enough that the downhaul, rotation, outhaul, and sheeting can control the sail shape pretty damn well. I am sure that AHPC/Red Line Racing setup the boats (thanks guys!) the best they could according to the conditions every day such that it was not an overwhelming variable. You get much better data holding the boats constant than introducing the additional variable set associated with differently tuned boats. Further, the beauty of multivariant regression analysis is that it works on averages and produces variable coefficients that can also be mathematically assessed in terms of reliability and probability. Obviously, there could also be outlyer tests conducted on the data to assess if a team's result(s) are out of the normal range of expected outcomes.
