title: Test Equality between Three Treatments under an Incomplete Block Crossover Design.
abstract: Under a random effects linear additive risk model, we compare two experimental treatments with a placebo in continuous data under an incomplete block crossover trial. We develop three test procedures for simultaneously testing equality between two experimental treatments and a placebo, as well as interval estimators for the mean difference between treatments. We apply Monte Carlo simulations to evaluate the performance of these test procedures and interval estimators in a variety of situations. We note that the bivariate test procedure accounting for the dependence structure based on the F-test is preferable to the other two procedures when there is only one of the two experimental treatments has a non-zero effect vs. the placebo. We note further that when the effects of the two experimental treatments vs. a placebo are in the same relative directions and are approximately of equal magnitude, the summary test procedure based on a simple average of two weighted-least-squares (WLS) estimators can outperform the other two procedures with respect to power. When one of the two experimental treatments has a relatively large effect vs. the placebo, the univariate test procedure with using Bonferroni's equality can be still of use. Finally, we use the data about the forced expiratory volume in 1 s (FEV1) readings taken from a double-blind crossover trial comparing two different doses of formoterol with a placebo to illustrate the use of test procedures and interval estimators proposed here.
authors.affiliation: a Department of Mathematics and Statistics , San Diego State University , San Diego , California , USA.
authors.forename: Kung-Jong
authors.initials: KJ
authors.lastname: Lui
mesh_terms: D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006801:Humans; D015233:Models, Statistical; D009010:Monte Carlo Method; D016896:Treatment Outcome
keywords: Crossover trial; Incomplete block; Interval estimation; Scheffe’s method; Test equality