Internal consistency and structure of the MMPI-2 substance abuse scales.

The purpose of this study is to evaluate the internal consistency and struc ture of the addiction scales of the MMPI-2: the MacAndrew Alcoholism Scale- Revised (MAC-R), the Addiction Acknowledgment Scale (AAS) and the Addiction Potential Scale (APS). Another objective of the study is to assess the dif ferences between the mean scores of the Mexican alcoholic and of the volunt eer subjects, in order to find out if the alcohol scales of the MMPI-2 disc riminate adequately between both groups. The inventory was administered to two samples of Mexican population; the first group consisted of 136 male su bjects who had alcoholism problems and a second group of 860 male volunteer s. The t Student test was calculated in order to identify the differences b etween the means in both groups; the internal consistency of the addiction scales was calculated by the alpha Cronbach test, and the internal structur e was estimated by factor analysis. The results indicate the existence of d ifferences between the group of normal subjects and that of the alcoholic p atients in the addiction scales (MAC-R, APS and AAS). The mean scores of th e alcoholic patients are higher than those of the volunteer subjects. The alpha Cronbach coefficient obtained by both groups in the addiction sca les show an adequate internal consistency, which indicates that the scales are also reliable for the Mexican population. With respect to the factorial analysis, results indicate that the addiction scales show validity in Mexi can alcoholics. From these results it may be concluded that: the MMPI-2 is adequate to identify personality traits in alcoholic patients, which are di fferent from other group personality traits. Addiction scales also clearly discriminate one group from the other.