A graphical presentation of the results of crossover trials.

1. Crossover designs are widely used in clinical trials. A graphical method of describing the data as well as visually indicating the extent of treatment * period interaction and overall treatment effect is presented. This plots the treatment differences between the periods for each individual against the mean of their treatment outcomes. It is recommended that this plot accompany the analysis of crossover trials in order to aid summary and interpretation especially for the non-statistician.