title: Power analysis on the time effect for the longitudinal Rasch model.
abstract: Statistics literature in the social, behavioral, and biomedical sciences typically stress the importance of power analysis. Patient Reported Outcomes (PRO) such as quality of life and other perceived health measures (pain, fatigue, stress,...) are increasingly used as important health outcomes in clinical trials or in epidemiological studies. They cannot be directly observed nor measured as other clinical or biological data and they are often collected through questionnaires with binary or polytomous items. The Rasch model is the well known model in the item response theory (IRT) for binary data. The article proposes an approach to evaluate the statistical power of the time effect for the longitudinal Rasch model with two time points. The performance of this method is compared to the one obtained by simulation study. Finally, the proposed approach is illustrated on one subscale of the SF-36 questionnaire.
authors.affiliation: Pharmacoepidemiologie et Mesures Subjectives en Sante, Faculte de Pharmacie, Universite de Nantes, 1 rue Gaston Veil, 44035 Nantes, France.
authors.forename: M L
authors.initials: ML
authors.lastname: Feddag
authors.forename: M
authors.initials: M
authors.lastname: Blanchin
authors.forename: J B
authors.initials: JB
authors.lastname: Hardouin
authors.forename: V
authors.initials: V
authors.lastname: Sebille
mesh_terms: D000203:Activities of Daily Living / Q000145:classification / Q000523:psychology; D005602:France; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000175:diagnosis / Q000523:psychology / Q000601:surgery*; D008137:Longitudinal Studies / Q000706:statistics & numerical data; D008432:Mathematical Computing; D015233:Models, Statistical; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data*; D011183:Postoperative Complications / Q000523:psychology; D011446:Prospective Studies; D011594:Psychometrics / Q000706:statistics & numerical data*; D011788:Quality of Life / Q000523:psychology; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires