R² (R squared) and adjusted R²

R² is the proportion of the differences (variance) in the predicted variable that the predictors explain together - between 0 and 1. Adjusted R² takes a little off, because every extra predictor raises R² slightly even if it adds nothing.

Example: R² = .15: time management and gender explain 15% of the differences in rehearsal strategies. Time management alone: R² = .08.

Caution: If an extra predictor barely raises R² and is not significant, it adds little.