I like the Worth magazine study from 2002. It ranked the schools by their feeding history. Example: Roxbury Latin in Mass., sent 21% of every graduating class to Harvard, Yale, Princeton over a 5 year period. In addition, they sent another 12% to Dartmouth, Stanford and Georgetown. I'm sure other variables come into play, such as, maybe they are sons of professors at the many elite colleges nearby. Point is, if you can routinely get into those schools, you can get into lesser schools. The admissions depts. don't like risk with border-line schools.
What is more telling is the curriculum. Every student must start learning Latin in 7th grade for a duration of 3 years. If they commit to Greek, they must study it for 2 years. Is it any wonder they do well on the verbal SAT section? Maybe we should emulate them instead of implementing that ridiculous Core Curriculum.