In the SPSS output tables below,the change amount in Adjusted R²from .754 to .771indicates _____.

Variables Entered/ Removeda Variables Variables Model Entered Removed Method X2, X1" Enter 2 Backward (criterion: X1 Probability of F-to-remove >= .100). a. Dependent Variable: Y b. All requested variables entered. Model Summary Adjusted R Std. Error of Model R R Square Square the Estimate .899 .809 .754 66075 N .892 .796 .771 .63867 a. Predictors: (Constant), X2, X1 b. Predictors: (Constant), X2