Construction of a depression scale with the Rasch model

This study examines the psychometric properties of a depression questionnaire. The goal was to improve the technical quality of traditional measures of depression in Spanish youth. 310 participants, aged 18-24 years, filled in the self-report questionnaire. The data were analyzed by means of the Rasch model. Results show that model fit, average item reliability (.97), and average person reliability (.88) are high. After deleting four indicators showing misfit and 12 showing sex bias, the resulting scale measures clinical depression objectively. Using this scale, the expected sex-related differences are found.