Applications of a sequential alternating treatment design.

We propose the use of a combined version of the alternating treatments and multiple baseline designs in situations in which a traditional baseline (no treatment) condition either does not provide an adequate contrast condition or is not feasible or practical due to clinical constraints. We refer to this design as a sequential alternating treatments design because two treatments are initially implemented in a random or counterbalanced fashion and are followed by a sequential change in one or both treatments across settings, subjects, or tasks. The effects of the independent variables are assessed first by analyzing the two series of data points representing the different treatments (relative effects) and then by assessing changes in one or both series, as application of the alternative treatment is introduced sequentially. The sequential application of treatment provides an analysis of control in the same manner as the multiple baseline design; the initial alternating treatments phase provides a contrast condition in much the same manner as a baseline condition. Applications of this design to the assessment of peer training and self-injurious behavior are described.