Box-Tidwell Transformation/Test

References

     Box, G. E. P. and Tidwell, P. W. (1962) Transformation of the
     independent variables.  _Technometrics_ *4*, 531-550.

     Fox, J. (2008) _Applied Regression Analysis and Generalized Linear
     Models_, Second Edition. Sage.

     Fox, J. and Weisberg, S. (2011) _An R Companion to Applied
     Regression_, Second Edition, Sage.

Load packages

library(car)

Test

Here income and education variables are tested for non-linear relationship to the mean prestige adjusting for type and squared women variables. Income variables is significant.

boxTidwell(prestige ~ income + education, ~ type + poly(women, 2), data = Prestige)
##           Score Statistic   p-value MLE of lambda
## income          -4.482406 0.0000074    -0.3476283
## education        0.216991 0.8282154     1.2538274
## 
## iterations =  8