Linearising the relationship between Y and X
Even though two variables, X and Y, are nonlinearly related, applying a nonlinear transformation to one or other of the variables can linearise the relationship. In other words, some transformation of X may be linearly related to some transformation of Y.
Transformation of X
In the following example, only transformations of the explanatory variable, X, will be considered.
Vitamin B and weight gain of rats
In the next page, we will examine how transformations of the response, Y, may also be used when there is curvature.