A comparison of the effectiveness of MMPI indices in the discrimination of brain-damaged and schizophrenic patients.

Assessed the effectiveness of 22 published MMPI procedures to differentiate organic brain syndrome (OBS) from schizophrenic (Sc) patients. Generally, each procedure previously has been suggested to have some effectiveness in making this differentiation. When assessed across studies, however, the S groups have differed on so many relevant variables (age, sex, clinical setting, etc.) that direct comparisons of their relative effectiveness cannot be made. In the current study the accuracy rates are presented for each of the 22 discrimination procedures with a sample matched on age, education, and IQ and also with an unmatched sample, all selected from the patient population at a neuropsychiatric setting. With the matched sample the Hs-Pt Index (Watson, Plemel , & Jacobs, 1978) and the Sc-O Scale, Unweighted Long form (Watson, 1971) reached statistical significance (p less than .10). With the unmatched sample both of the above procedures plus the OBS Signs procedure ( Markowitz , 1973) and P-O Scale (Watson & Plemel , 1978) reached statistical significance (p less than .10). Overall accuracy rates of those procedures found to be statistically significant ranged from 61.5 to 70.0%. These accuracy rates compare favorably to those obtained with more complex and time-consuming neuropsychiatric batteries.