Crossover trials, degrees of freedom, the carryover problem and its dual

S. J. Senn*, H. Hildebrand

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

30 Citations (Scopus)


The problem of carryover in crossover trials has received a great deal of attention in the statistical literature. Carryover is just one form of period by treatment interaction; yet a parallel problem of patient by treatment interaction, which may be regarded as dual to that of carryover, has received little attention. We suggest that the phenomenon of patient by treatment interaction requires a repeated measures approach to the analysis of crossover trials. A simple solution using predefined contrasts is presented and illustrated by example.

Original languageEnglish
Pages (from-to)1361-1374
Number of pages14
JournalStatistics in Medicine
Issue number9
Publication statusPublished - Sept 1991
Externally publishedYes


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