In a recent book, Lorr and Associates5 presented the rationale and some procedures for a quantitative approach to the problem of identifying classes or types of psychotic patients. As part of the series of studies they identified and replicated six syndrome-based psychotic patient types. They defined a psychotic type as a class of patients who could be characterized in the same way on a common set of variables or measures. They used ten syndrome scores in the domain of observable psychotic behavior and symptomatology as the basic data for their typing analyses. The syndrome scores had been derived from an earlier series of factor analyses3,4 of the behavior of psychotics during psychiatric interviews as rated on the Inpatient Multidimensional Psychiatric Scale (IMPS).
The typing studies used the product-moment correlation between persons (Q) as the index of similarity between IMPS pro-files. Statistical analyses of
McNAIR DM, LORR M, HEMINGWAY P. Further Evidence for Syndrome-Based Psychotic Types. Arch Gen Psychiatry. 1964;11(4):368-376. doi:10.1001/archpsyc.1964.01720280014003