How much is there a self-selection bias in the results? IB programs are notoriously rigorous and tough. One could imagine that IB participants already exhibited higher levels of aptitude and achievement. Not surprisingly, their subsequent college performance is elevated. A private high school here in SF will be adding IB this fall, and I know two kids who are planning to enroll in the program. Both are already stellar students, which makes me wonder if “willingness to do IB” is the key factor, not the program itself.
BTW: the program does sound fantastic.