TY  - JOUR
A1  - Godolphin, PJ
A1  - Godolphin, EJ
KW  - Crossover design
KW  -  subject drop-out
KW  -  missing data
KW  -  clinical trial
KW  -  uniformly balanced repeated measurement design
KW  -  perpetually connected
EP  - 800
IS  - 3
Y1  - 2019/03/01/
TI  - Robustness of crossover trials against subject drop-out - Examples of perpetually connected designs
VL  - 28
SN  - 1477-0334
N2  - When performing a repeated measures experiment, such as a clinical trial, there is a risk of subject drop-out during the experiment. If one or more subjects leave the study prematurely, a situation could arise where the eventual design is disconnected, implying that very few treatment contrasts for both direct effects and carryover effects are estimable. This paper aims to identify experimental conditions where this problem with the eventual design can be avoided. It is shown that in the class of uniformly balanced repeated measurement designs consisting of two or more Latin squares, there are planned designs with the following useful property. Provided that all subjects have completed the first two periods of study, such a design will not be replaced by a disconnected eventual design due to drop-out, irrespective of the type of drop-out behaviour that may occur. Designs with this property are referred to as perpetually connected. These experimental conditions are identified and examined in the paper and an example of at least one perpetually connected uniformly balanced repeated measurement design is given in each case. The results improve upon previous contributions in the literature that have been confined largely to cases in which drop-out occurs only in the final periods of study.
SP  - 788
AV  - public
ID  - discovery10083383
UR  - https://doi.org/10.1177/0962280217736541
N1  - This version is the author accepted manuscript. For information on re-use, please refer to the publisher?s terms and conditions.
JF  - Statistical Methods in Medical Research
PB  - SAGE PUBLICATIONS LTD
ER  -