[Attempts at a nosological classification with two standardized psychiatric rating scales (author's transl)]

Three different procedures for classification of psychiatric patients, a modified form of Q factor analysis, the classical discriminant analysis and a simple procedure based on clinical concepts, were compared empirically. On the basis of the psychopathological state rated by means of the Inpatient Multidimensional Psychiatric Scale (IMPS) and psychopathological and somatic scales of the AMP documentation system (AMP scale), the three procedures were applied in order to reproduce the psychiatric diagnosis. The classification was made by paired comparison of the following four diagnoses: schizophrenia, paranoid form (n = 45), schizophrenia, unspecified form (n = 47), depressive psychosis (n = 44), and depressive neurosis (n = 53). The procedures were evaluated according to their crossvalidation results. The mean percentages of correct classification were the following: 83% for the modified form of Q factor analysis, 77% for the classical discriminant analysis, 73% for the simple procedure based on clinical concepts using the IMPS, and 79% for the same procedure, but using the AMP scale, all three procedures reaching about the same level of validity.