Stability and Internal Consistency of the Offer Self-Image Questionnaire: A Study of Finnish Adolescents

Reliability of the Offer Self-Image Questionnaire (OSIQ) was assessed with two measures—internal consistency and stability—in Finnish children aged 13. The OSIQ was administered to 268 normal 13-year-old pupils (129 girls and 139 boys). Three weeks later, a third of the pupils (N = 88) were randomly selected for retesting. Eighty-three teenagers completed the questionnaire in an acceptable manner. The internal consistency of the test was verified for each scale using Cronbach α. To estimate the stability of the test, Pearson correlation coefficients were calculated, and the mean raw scores for each scale were compared with those in the retest. The internal consistency of the test was fairly good (α = 0.54–0.84) for the majority of scales, except for scales S5 and S12 (α = 0.30–0.41). The stability of scales S1, S4, S5, S7, and S10 was good. On the basis of these two measures, we conclude that for Finnish adolescents, the OSIQ is sufficiently reliable only with respect to scales S1, S4, S7, and S10.