a friend who works for the Church shared some numbers with me years ago on a study that was done comparing BYU with institute programs and their effectiveness at long-term activity in the Church. I do not remember the actual numbers but was very surprised how much more likely a graduate at BYU is to stay active. Again, I do not remember the actual numbers but it was enough for me to make a decision to try and steer my kids in that direction.
Maybe the friend was citing a study that he heard second hand and the whole thing is ficticious. Don't shoot the messenger. FWIW, I have attended two other universities other than BYU. I know what the environment is like.