Selina Kallinger1, Henry Scharm1, Maren Boecker2, Thomas Forkmann3, Harald Baumeister1. 1. 1 Department of Clinical Psychology and Psychotherapy, Institute of Psychology and Education, University of Ulm, Ulm, Germany. 2. 2 Institute of Medical Psychology and Medical Sociology, University Hospital of RWTH Aachen, Aachen, Germany. 3. 3 Department of Clinical Psychology, University of Duisburg-Essen, Essen, Germany.
Abstract
OBJECTIVE: To calibrate an item bank of anxiety-related questions for use in orthopedic patients within a computer-adaptive test. DESIGN: This is a psychometric study. SETTING: The sample of orthopedic patients was recruited in two orthopedic rehabilitation clinics in Germany. SUBJECTS: A total of 474 orthopedic rehabilitation patients were recruited for this study. INTERVENTIONS: Not applicable. MAIN MEASURES: The main measure is an adapted version of an existing anxiety item pool for cardiovascular rehabilitation patients. RESULTS: The results of the confirmatory factor analysis and Mokken analysis confirmed a one-factor structure and double monotonicity. An anxiety item bank (48 items) could be developed and calibrated using Rasch analysis. It fitted to the Rasch model with a non-significant item-trait interaction (χ2(203) = 172.59; P = .94) and was free of differential item functioning. Unidimensionality could be verified and the person separation reliability was .96. The category threshold parameters varied between 4.72 and 3.16 (7.88 logits). CONCLUSION: The unidimensional anxiety item bank provides the basis for a computer-adaptive test to assess a wide range of anxiety in rehabilitation patients with orthopedic diseases with very good psychometric characteristics.
OBJECTIVE: To calibrate an item bank of anxiety-related questions for use in orthopedic patients within a computer-adaptive test. DESIGN: This is a psychometric study. SETTING: The sample of orthopedic patients was recruited in two orthopedic rehabilitation clinics in Germany. SUBJECTS: A total of 474 orthopedic rehabilitation patients were recruited for this study. INTERVENTIONS: Not applicable. MAIN MEASURES: The main measure is an adapted version of an existing anxiety item pool for cardiovascular rehabilitation patients. RESULTS: The results of the confirmatory factor analysis and Mokken analysis confirmed a one-factor structure and double monotonicity. An anxiety item bank (48 items) could be developed and calibrated using Rasch analysis. It fitted to the Rasch model with a non-significant item-trait interaction (χ2(203) = 172.59; P = .94) and was free of differential item functioning. Unidimensionality could be verified and the person separation reliability was .96. The category threshold parameters varied between 4.72 and 3.16 (7.88 logits). CONCLUSION: The unidimensional anxiety item bank provides the basis for a computer-adaptive test to assess a wide range of anxiety in rehabilitation patients with orthopedic diseases with very good psychometric characteristics.