R-squared Score

A statistical measure that represents the proportion of variance explained by a regression model

$$R^2=1-\frac{{\sum }_{i=1}^n(y_i-\widehat{y_i}{)}^2}{{\sum }_{i=1}^n(y_i-\overline{y_i}{)}^2}$$

(notice the difference between $\widehat{y_i}$ and $\overline{y_i}$)