I’d say the issues pertaining to ranking private high schools (prep schools) are similar to those of ranking colleges and universities. A big difference is the extent to which the Prep schools have discouraged and been successful at preventing rankings. All the arguments about not ranking prep schools are true about colleges too. It’s just that it has been far more difficult for outsiders to obtain accurate information about prep schools whereas colleges and universities have been unable to withhold the data, in most cases.