An ordinal evaluation of categorical judgement data by random utilities and a corresponding correlation analysis

Categorical judgement data are analyzed along the lines of random utility theory. A class of orders is introduced (categorical weak orders); their characteristic vectors are regarded as points in a Euclidean space; their convex hull forms a polytope whose facets are fully characterized. This polytope is shown to correspond to an order polytope. Furthermore, its relation to the biorder polytope is pointed out. The convex representations of a given point of the polytope are discussed. The impact of these results on the methods of analyzing data arising from a categorical judgement procedure is outlined. In particular, some consequences are drawn with respect to the usual evaluation of correlations of such data.