California drop-out study

California dropout spike coincided with onset of exit exams
In the first year that California high school students were required to pass exit exams, some 24,000 seniors dropped out, according to a report presented to the state's board of education. The report recommended California consider alternative means for seniors to prove their proficiency.
Human Resources Research Organization. (2007). Independent evaluation of the California high school exit examination. Alexandria, VA: Human Resources Research Organization.
http://www.cde.ca.gov/ta/tg/hs/documents/ab1609srv2appa.pdf