Flexibility of single-subject experimental designs. Part I: Review of the basics of single-subject designs.

The discussion in this article is directed at a brief review of the basic components of single-subject experimental designs. It sets out to present some of the technical and practical advantages in developing single-subject designs to evaluate potential treatment variables and treatments. The point is made that the designs are specifically structured for applied, intervention research. In addition to explaining how the basic AB components function to allow for a controlled evaluation, a short review is included of other factors important to the scientific method such as operational definitions, reliability, repeated measures, and internal and external validity. The article serves as a foundation for the following two articles that are directed at demonstrating the flexibility of single-subject experimental studies.