Unofficial preliminary statistics of this year’s AP exams have been posted at 2011 AP Exam Score Distribution. It looks like the failure rates on AP exams are once again quite high.
The exam with the most 1s is AP biology, with 35.1% 1s. Another 14.7% got 2s, making a failure rate of 49.8%. Almost half the students taking the AP bio exam are failing it. Either the exam is too hard or too many unprepared students are taking it. I think that there is a little of both on this exam, as it requires memorizing huge numbers of factoids and students and schools still think of biology as the “easy” science, because it uses the least math. This is a serious error in thinking—AP physics is much simpler conceptually with much less to memorize.
World History is the worst, failing 51.3%. Again, I suspect that the problem is having to memorize huge numbers of factoids. Another AP test with a huge failure rate is Human Geography at 48.9%. I’m actually surprised that this AP exam even exists, as geography is not a common college course (it is mostly a high-school course).
The exam with the lowest failure rate is Chinese Language and Culture (4.5%), though for non-heritage speakers the failure rate goes up to 21%. The Studio Art exams have very few 1s, but a lot of 2s, for failure rates of 27.7% to 39.2%.
In general, it seems like the highest failure rates are associated with exams that require memorization and the lowest with exams that require skills.
With a median failure rate around 38%, it is clear that a lot of students taking AP exams are not prepared for them at all. I suspect that the problem comes in part from the attempts to rate high schools by how many AP exams their students take (rather than how many they pass). Schools have a perverse incentive to push kids to take the exams, but little incentive to make sure that they learn the material.
Where there are multiple levels of exams (Physics and Calculus) the failure rate is much higher for the easier exam (Physics B 39.6%, Physics C mechanics 27.1%, Physics C electricity and magnetism 29.5%; Calculus AB 44.2%, Calculus BC 19.5%). Because the higher-level exam is certainly the harder one, this indicates that the high failure rates are probably not due to the exams being too difficult, but because the students are not prepared for them.
I don’t know how the AP pass rates compare to college freshman pass rates in the corresponding courses. Universities gather such statistics, but make them hard to access. Even faculty at the university have to jump through various bureaucratic hoops to get access to the data.