title: Sample size determination for longitudinal designs with binary response.
abstract: In this article, we develop appropriate statistical methods for determining the required sample size while comparing the efficacy of an intervention to a control with repeated binary response outcomes. Our proposed methodology incorporates the complexity of the hierarchical nature of underlying designs and provides solutions when varying attrition rates are present over time. We explore how the between-subject variability and attrition rates jointly influence the computation of sample size formula. Our procedure also shows how efficient estimation methods play a crucial role in power analysis. A practical guideline is provided when information regarding individual variance component is unavailable. The validity of our methods is established by extensive simulation studies. Results are illustrated with the help of two randomized clinical trials in the areas of contraception and insomnia.
authors.affiliation: Clinical Research Center and Department of Neurology, Boston Children's Hospital, Harvard Medical School, 21 Autumn St., Boston, MA 02215, U.S.A.
authors.forename: Kush
authors.initials: K
authors.lastname: Kapur
authors.forename: Runa
authors.initials: R
authors.lastname: Bhaumik
authors.forename: X Charlene
authors.initials: XC
authors.lastname: Tang
authors.forename: Kwan
authors.initials: K
authors.lastname: Hur
authors.forename: Domenic J
authors.initials: DJ
authors.lastname: Reda
authors.forename: Dulal K
authors.initials: DK
authors.lastname: Bhaumik
mesh_terms: D006801:Humans; D008137:Longitudinal Studies; D015233:Models, Statistical; D012107:Research Design; D018401:Sample Size
keywords: Fisher information matrix; Gaussian quadrature; logistic mixed-effects model; power; type I error rate