A statistic indicating the goodness of fit of a model, representing the proportion of the variance in the dependent variable that is predictable from the independent variable(s). An R² of 1 indicates a perfect fit, while 0 indicates no linear relationship. It is calculated as [latex]R^2 \equiv 1 – \frac{SS_{res}}{SS_{tot}}[/latex], where [latex]SS_{res}[/latex] is the residual sum of squares.
