Public schools are ranked according to a ratio devised by [WaPo edu-blogger] Jay Mathews: the number of Advanced Placement, Intl. Baccalaureate and/or Cambridge tests taken by all students at a school . . . divided by the number of graduating seniors.Newsweek's ranking don't consider the percentage of students who pass or fail the AP tests.
Because the failure rate is increasing (41.5% failed last year, up from 36.5% in 1999) Newsweek's rankings have become that much less reliable.
The single-criterion rating system has worked reasonably well so far. But at some point Newsweek will have to change it's formula to include pass/fail rates.
*It's actually called the Challenge Index, and it includes partipation in the AP and similar college-level tests.