According to a longitudinal study analyzing statistics on private and public schools attendance at University of Michigan in 2008 there were definite differences between the results of students. Out of the study group there were 76% public and 24% private students. Of the public school students there were 72% that graduated high school and 28% that did not.
Of the students that graduated public high school 65% attended college, and 79% of private school students went to college. Of the 65% that attended college only 36% received a bachelors degree or higher. However, of the 79% graduated private schools, 52% received a bachelors degree or higher.
As a result of this study one can see that there is a measurable difference in the statistics on private and public schools attendance. One could conclude that there is definitely a higher rate of private school students who actually attain a degree.