I have one thought about this study questioning the value of Advanced Placement testing. I graded AP U.S. History exams for 3 years. The pass rate was about 55% (assuming a 3 is a pass). I would argue the number of students who wrote a test that showed even a minimally competent knowledge of the material, one that would get, say, a B- or C+ in a college level freshman class, was about 10%. The idea that students are getting college credit for this stuff is a joke.