The Equivalent Materials Design can be represented as follows:

This design is similar to the equivalent time samples design, but the different experimental situations include different though equivalent materials. I really cannot think of a medical example of this design. Some of you may be able to help me out here.

This design is useful where the effects of the experimental treatment are enduring, so that the different treatments and repeats of treatments must be applied to non-identical content. It has been used, for example, in studies of distributed versus massed practice learning. One or more persons are presented with a list of nonsense syllables which are then learned under either distributed or massed practice conditions. The measure is total time on task to perfect memory of the list. Once someone has learned a particular set of nonsense syllables, it is necessary to provide an equivalent list for further trials.