The R² (i.e., R-squared)tells us the percentage of the variation in the dependent variable (cost)that is explained by variation in the independent variable (activity).

R-squared

A statistical measure that represents the proportion of the variance for a dependent variable that's explained by an independent variable or variables in a regression model.

Dependent Variable

A variable that responds to some causal factor; total cost is the dependent variable, as represented by the letter Y, in the equation Y = a + bX.

Independent Variable

A variable in an experiment that is manipulated to observe its effect on the dependent variable.