The IIS-32: a brief inventory of interpersonal strengths.

The inventory of interpersonal strengths (IIS-64; Hatcher & Rogers, 2009 ) is a 64-item self-report measure based on the interpersonal circle (Pincus & Gurtman, 2006 ) with 8 subscales, or octants, that measure positive interpersonal characteristics covering the full range of the interpersonal circle. The IIS-64 is a valid and psychometrically robust measure of positive interpersonal features. However, because assessment time is precious in many contexts, briefer instruments might be of considerable value. We report the development of a brief version of the IIS-64 that retains the strong measurement characteristics of the original. Nonparametric item response theory methods were utilized in conjunction with factor-analytic item selection procedures in the original IIS-64 derivation sample of 1,377 to derive a 32-item version of the IIS that best represented a circumplex structure. Circumplex structure was confirmed in an additional college sample (N = 956) and in a clinical sample (N = 496). Convergence with the IIS-64 was confirmed, as were alpha and test-retest reliability. Convergent validity was demonstrated with measures of the Big Five factors. The IIS-32 should prove to be a useful and flexible measure of interpersonal strengths.