Randomization tests for restricted alternating treatments designs.

Alternating Treatments Designs (ATD) with random assignment of the treatments to the measurement times provide very powerful single-case experiments. However, complete randomization might cause too many consecutive administrations of the same treatment to occur in the design. In order to exclude these possibilities, an ATD with restricted randomization can be used. In this article we provide a general rationale for the random assignment procedure in such a Restricted Alternating Treatments Design (RATD), and derive the corresponding randomization test. A software package for randomization tests in RATD, ATD and other single-case experimental designs [Van Damme & Onghena Single-case randomization tests, version 1.1, Department of Psychology, Katholieke Universiteit Leuven, Belgium] is discussed.