Hello Steve,
I was thinking physically. It involves lifting one end of the car up and measuring how much weight transfers to the other axle. So not simple to do. Need weighpads and some equipment and strategy for lifting the car safely. And a finished car of course. I've never attempted it myself but the information would enable anyone to calculate the weight transfer due to braking and therefore accurately predict the likelihood of rear lock with a particular brake configuration.
Cheers,
Keith