A note on ridge regression modeling techniques

In this study, the techniques of ridge regression model as alternative to the classical ordinary least square (OLS) method in the presence of correlated predictors were investigated. One of the basic steps for fitting efficient ridge regression models require that the predictor variables be scaled to unit lengths or to have zero means and unit standard deviations prior to parameters’ estimations. This was meant to achieve stable and efficient estimates of the parameters in the presence of multicollinearity in the data. However, despite the benefits of this variable transformation on ridge estimators, many published works on ridge regression practically ignored it in their parameters’ estimations. This work therefore examined the impacts of scaled collinear predictor variables on ridge regression estimators. Various results from simulation studies underscored the practical importance of scaling the predictor variables while fitting ridge regression models. A real life data set on import activities in the French economy was employed to validate the results from the simulation studies.