Psychometrics of the personal questionnaire : a client-generated outcome measure

Elliott, Robert and Wagner, John and Sales, Celia M. D. and Rodgers, Brian and Alves, Paula and Cafe, Maria J. (2016) Psychometrics of the personal questionnaire : a client-generated outcome measure. Psychological Assessment, 28 (3). pp. 263-278. ISSN 1040-3590

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    Abstract

    We present a range of evidence for the reliability and validity of data generated by the Personal Questionnaire (PQ), a client-generated individualized outcome measure, using five data sets from three countries. Overall pre-therapy mean internal consistency (alpha) across clients was .80; within-client alphas averaged .77; clients typically had one or two items that did not vary with the other items. Analyses of temporal structure indicated high levels of between client variance (58%), moderate pre-therapy test-retest correlations (r =.57), and high session-to-session lag-1 autocorrelations (.82). Scores on the PQ provided clear evidence of convergence with a range of outcome measures (within-client r = .41). Mean pre-post effects were large (d = 1.25). The results support a revised caseness cut-off of 3.25 and a reliable change interval of 1.67. We conclude that PQ data meet criteria for evidence-based, norm-referenced measurement of client psychological distress for supporting psychotherapy practice and research.