Abstract
This study used a confirmatory factor analysis procedure, the Oblique Multiple Group Method (OMG), with the Brief Psychiatric Rating Scale (BPRS) on a sample of homeless individuals who had both a severe mental illness and a substance use disorder. The hypothesized five-factor model of Guy (1976) accounted for 93% of the possible variance, and all the appropriate scales had their highest loading on their respective hypothesized factor. In addition, the Guy model accounted for more variance than did an alternative model. The five factors were labelled: thinking disorder, anergia, anxiety-depression, hostility-suspicion, and activity.