Categorical versus dimensional classification: Implications from and for research

This paper discusses the implications from research and for research of a dimensional model of classification. Literature is discussed with respect to face validity, utility and descriptive validity, the empirical support for the DSM-III-R categorical distinctions, reliability and concurrent validity, and taxometric analyses. The conclusion of the review is that researchers should use more quantitative (dimensional) assessments, at least in addition to the DSM-III-R categorical diagnoses. Research concerned with the etiology, pathology, prognosis, and treatment of the personality disorders will be more powerful and informative if personality disorders are assessed as continuous rather than as discrete variables.