Single-case Research Designs

ingle-case research designs are a diverse and powerful set of procedures useful for demonstrating causal relations among clinical phenomena. Although such designs are flexible, efficient, and have been used to make key advances since the earliest days of psychological science, they are currently extremely underused by psychological scientists and clinicians. We review the historical and theoretical foundations of single-case research designs, including case studies, quasi-experimental designs, and experimental designs used in single-case or small-group studies. We also summarize the methodological requirements, primary design options, and challenges and limitations of each approach. Recent examples of each design are provided to illustrate the usefulness of these valuable—albeit somewhat forsaken—research methods for scientific and clinical advancement.