Mallows, C.L. (1986, ASQC and the American Statistical Association) AT&T Bell Laboratories, Murray Hill, NJ
A simple way of encouraging a nonlinear effect in a regression model to show itself in a partial residual (parres) plot (component-plus-residual plot) is to include a single quadratic term in the regression. It is computationally cheap to do this for each of the independent variables. Examples show that the resulting set of augmented partial residual plots gives insights that are not available from standard parres or added-variable plots.