On the use of ordered factors as explanatory variables

Abstract

Consider a regression or some regression-type model for a certain response variable where the linear predictor includes an ordered factor among the explanatory variables. The inclusion of a factor of this type can take place is a few different ways, discussed in the pertaining literature. The present contribution proposes a different way of tackling this problem, by constructing a numeric variable in an alternative way with respect to the current methodology. The proposed techniques appears to retain the data fitting capability of the existing methodology, but with a simpler interpretation of the model components.