The true return to college heavily depends on the probability of successful completion. That probability in turn heavily depends on pre-college academic performance. How heavily? Check out these three graphs from Bound, Lovenheim, and Turner’s “Why Have College Completion Rates Declined?” (American Economic Journal 2010). BLT compare results for the NLS72 (high school graduation cohort of 1972) and NELS:88 (high school graduation cohort of 1992), using a standardized high school math test to measure pre-college performance.
First, check out your probability of trying college if you finish high school.