Supporting information may be found in the online version of this article.
Parallel, AA/BB, AB/BA and Balaam's design: efficient and maximin choices when testing the treatment effect in a mixed effects linear regression†
Article first published online: 15 FEB 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Volume 11, Issue 2, pages 97–106, March/April 2012
How to Cite
Candel, M. J. J. M. (2012), Parallel, AA/BB, AB/BA and Balaam's design: efficient and maximin choices when testing the treatment effect in a mixed effects linear regression. Pharmaceut. Statist., 11: 97–106. doi: 10.1002/pst.502
- Issue published online: 14 MAR 2012
- Article first published online: 15 FEB 2012
- AB/BA cross-over design;
- Balaam's design;
- efficient design;
- maximin design;
- (extended) parallel design
When examining the effect of treatment A versus B, there may be a choice between a parallel group design, an AA/BB design, an AB/BA cross-over and Balaam's design. In case of a linear mixed effects regression, it is examined, starting from a flexible function of the costs involved and allowing for subject dropout, which design is most efficient in estimating this effect. For no carry-over, the AB/BA cross-over design is most efficient as long as the dropout rate at the second measurement does not exceed 2ρ/(1 + ρ), ρ being the intraclass correlation. For steady-state carry-over, depending on the costs involved, the dropout rate and ρ, either a parallel design or an AA/BB design is most efficient. For types of carry-over that allow for self carry-over, interest is in the direct treatment effect plus the self carry-over effect, with either an AA/BB or Balaam's design being most efficient. In case of insufficient knowledge on the dropout rate or ρ, a maximin strategy is devised: choose the design that minimizes the maximum variance of the treatment estimator. Such maximin designs are derived for each type of carry-over. Copyright © 2012 John Wiley & Sons, Ltd.