Building Models with Categorical Variables

Abstract

This chapter describes how to build models using multiple variables and how to define categorical variables in a simple way. It also describes how data from an industrial case study are used to illustrate the contribution of an additional variable in deriving multiple models from a single dataset. Software size is recognized as a key factor in the construction of models estimating project effort. The size of the functionality of the projects was measured with the COSMIC functional size method. Regression models with multiple independent variables are investigated to analyze how these additional variables contribute individually to the relationship between size and effort.