Power and sample size determination in the Rasch model: evaluation of the robustness of a numerical method to non-normality of the latent trait.

ABSTRACT: Patient-reported outcomes (PRO) have gained importance in clinical and epidemiological research and aim at assessing quality of life, anxiety or fatigue for instance. Item Response Theory (IRT) models are increasingly used to validate and analyse PRO. Such models relate observed variables to a latent variable (unobservable variable) which is commonly assumed to be normally distributed. A priori sample size determination is important to obtain adequately powered studies to determine clinically important changes in PRO. In previous developments, the Raschpower method has been proposed for the determination of the power of the test of group effect for the comparison of PRO in cross-sectional studies with an IRT model, the Rasch model. The objective of this work was to evaluate the robustness

SUBMITTER: Guilleux A 

PROVIDER: S-EPMC3888396 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature