title: Comparisons within randomised groups can be very misleading.
authors.affiliation: Department of Health Sciences, University of York, York YO10 5DD. martin.bland@york.ac.uk
authors.forename: J Martin
authors.initials: JM
authors.lastname: Bland
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Altman
mesh_terms: D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*; D012107:Research Design