Robust procedures for analysing a two-period cross-over design with baseline measurements.
Patel analysed a two-period cross-over design with baseline measurements assuming bivariate normality for the joint distribution of the period responses. In this paper, we propose non-parametric methods for analysing this design, including the use of the Wilcoxon rank sum test to derive the preliminary tests from the baseline measurements. We fit a robust regression line of the treatment response on baseline for each period and compute residuals. We also fit a robust locally weighted regression as an alternative method for computing residuals. Then, following Koch's procedure, we analyse the residuals for testing the significance of the treatment x period interaction and the treatment difference. We provide a numerical example to illustrate the methods.
Tsai
K T
KT
Schering-Plough Research Institute, Kenilworth, NJ 07033, USA.
Patel
H L
HL
D017321:Clinical Trials, Phase I as Topic; D018592:Cross-Over Studies; D003627:Data Interpretation, Statistical; D006801:Humans; D016018:Least-Squares Analysis; D016014:Linear Models; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric; D013997:Time Factors; D016896:Treatment Outcome