Categorizing Individuals: An Alternative to Linear Analysis

A common problem concerns the relations between children's behaviour or characteristics at one age or in one situation, and those shown later or in another context. It is argued here that Pearson or rank order correlations may not be ubiquitously suitable for assessing such relations, primarily because independent variables (IV's) and dependent variables (DV's) may be related for only some of the children (e.g., those high on the IV may tend to be high on the DV, but for children with lower scores on the IV there may be no relation to the scores on the DV). Categorization procedures can help. It is shown that the use of Pearson correlations, multiple regression, continuous discriminant analysis and discrete discriminant analysis on the same data sets show up different types of relations between IV's and DV's. Categorization procedures can also facilitate examination of individual cases.