The graphical representation of clinical trials with particular reference to measurements over time

Clinical trials are frequently analysed as if they were surveys when they are in fact experiments. In particular the experimental basis of clinical trials is rarely reflected in the graphs which are used to illustrate them. Proposals are made, and illustrated by example, as to how appropriate figures may be devised, both for parallel-group designs and for crossover trials, to illustrate the experimental nature of clinical trials with measurements over time.