Multivariate statistical methods and problems of classification in psychiatry.

This paper is concerned with the use of multivariate statistical methods in relation to classification in psychiatry. There are two aspects of classification: the classification of symptoms to form syndromes and of patients into diagnostic groups. Critical papers are reviewed, and proposed severe limitations on the methods answered. The use of multivariate methods has increased objectivity and agreement between investigators, but differences remain, largely on issues in statistical logic, which must be resolved.