Depression factors in depressed and in heterogeneous in-patient samples.

Lorr, Klett, and McNair (1963) noted that factorial studies limited to patients of one diagnostic category exhibited the 'effects of restriction in various sources of population variance and limitations on defining variables'. Factor analyses of depressive symptoms have for the most part utilized patients whose clinical diagnosis was depression (Hamilton and White, 1959; Hamilton, 1960; Overall, 1962; Kiloh and Garside, 1963; Rosenthal and Klerman, 1966; Raskin, Schulterbrandt, Reatig, and Rice, 1967). By limiting his sample to such subjects, Overall (1962) hoped to minimize any general depression factor and focus on individual differences among depressed patients. Hamilton (1960), whose goal was quantification of interview behaviour of depressed patients, felt that specific symptoms could not validly be interpreted or weighted apart from diagnostic context. In some instances, factor analytic method has been used to delineate in samples of depressed subjects behaviour patterns corresponding to aetiological concepts-that is, endogenous vs. neurotic or reactive depression (Hamilton and White, 1959; Kiloh and Garside, 1963; Rosenthal and Klerman, 1966). Any investigator who has attempted to select a sample of depressed in-patients will attest to the prevalence of 'mixed pictures'. Depressive symptomatology often appears in a context of schizophrenia or other primary diagnosis (Hinsie and Campbell, 1960; Spitzer and Wilson, 1968). Objective measurement of such symptoms, wherever they may occur, is, nevertheless, basic to accurate appraisal of treatment effects. Behavioural rating