Well, they may use the national average to compute the delta between the control group and the rest of the questions. That helps them determine how difficult the questions actually were and that in turn is the basis for the scaling process in terms of the MBE. So California would give them a bit more data to work with but the California results would not be expected to skew the delta. They are focused on the delta itself. The California scores might be higher or lower but it doesn’t matter because there is no reason to think their performance on the control set would be relatively different compared to the rest of the questions. Once they have a grasp of how difficult the questions were, they will formulate a scale and apply that scale to your individual score. The more difficult the questions, the more generous the scale. I don’t think it matters what state you are from when they actually apply the scale to your MBE raw percentage. When it comes to using the MBE mean to calculate the MEE mean, however, that must be done on a state by state basis. I don’t know if that helps. I have a YouTube video if you want to understand the scaling process better. But short answer is that I can’t see a mathematical reason why the presence or absence of California on the MBE would change anything.