Correspondence Analysis: Theory, Practice and New Strategies

4Simple Correspondence Analysis

4.1 Introduction

The graphical depiction of the association between categorical variables can be undertaken in many different ways. Chapter 1 provides a description of some common methods for visualising univariate and bivariate categorical variables. Our focus is on the correspondence analysis of a contingency table, whether it be a cross-classification of only two variables, or of many. The most simple case, where correspondence analysis is applied, is for the graphical depiction of association between the variables of a two-way contingency table. Such a variant of correspondence analysis is referred to as simple correspondence analysis. The use of the word simple does not imply that the method is necessarily easy. Instead, it refers to the most simple type of contingency table the technique analyses –that is a two-way contingency table.

What is now well understood as correspondence analysis has European origins. It has long been recognised that the quantification of association between two (or more) categorical variables has its roots in England. Some of the pioneering work of R.A. Fisher, Karl Pearson, Frank Yates and George U. Yule formed the foundation of the numerical aspects of correspondence analysis. However, it was not until the 1960s when Jean-Paul Benzécri and his team at the University of Paris, France, proposed a technique with a heavy graphical component to this work which we now recognise as correspondence analysis. It has since ...