An Approach to the Multivariate Analysis of Ordinal Data

Techniques of multivariate analysis currently in use are rarely appropriate to an ordinal level of measurement; they are designed either for interval measurement or for nominal categories. It is possible to construct a hypothetical example in which the neglect of the ordered nature of a control variable leads to erroneous conclusions when three ordered variables are jointly cross-classified. This result suggests that, in addition to traditional methods, an additional criterion, based on the logic of partial rank correlation, should be considered in summarizing such data.