Whenever there is more than one independent variable, adjusted R2 is less than R2. Adding a new independent variable will increase R2, but may either increase or decrease adjusted R2.
R2 adjusted = 1 − [((n − 1) / (n − k − 1)) × (1 − R2)]
Where:
n = number of observations
K = number of independent variables
R2 = unadjusted R2
