Crossover experiments, also called the repeated-measurements design, is a study design in which all experimental units are exposed to all treatments in different periods. Crossover experiments are generally used in psychology, the pharmaceutical industry, agriculture, and medicine.

Crossover designs are performed even with smaller sample sizes since the samples can act as their controls. These are better than simple randomized trials since patients are exposed to all the treatments. Furthermore, cross-over designs are preferred to compare the bioavailability or ingestion of the drug in the human body and compare it with a reference drug. This method is unsuitable if the disease is chronic and stable and the drug should not completely cure the disease condition.