The incremental variance problem: enhancing the predictability of academic success in an urban, commuter institution.

The authors identified variables that enhance the predictability of academic performance and retention in an urban, commuter college. They used a longitudinal design with 2 waves of data collection: prior to 1st-semester attendance and again 6 semesters later. The results support the following conclusions: (a) After controlling for precollege indices of academic ability, specific variables within demographic, personal behavior, expectations, and attitudinal domains improved the predictability of grade point average by 15.5% for Whites and 20.3% for Blacks; overall, these analyses accounted for 61% of the variance in grade point average for Whites and 47% for Blacks; (b) for retention, the comparable increment in predictability was 2.5% for Whites and less than 1% for Blacks; overall, the percentage of retention variance accounted for was 42% for Whites and 29% for Blacks; and (c) a paradoxical finding was the combination of a positive correlation between high school average and students' expected grades on tests and a negative correlation between expected and actual grades. The paradox is resolved by citing data that demonstrate (a) a disparity between high school grades and independently measured academic accomplishment; (b) the consequent false attributions students draw about their academic abilities; and (c) the impact of these false attributions on the priority students place on their academic responsibilities.