Single case studies in psychology and psychiatry.

Single-case experimental designs are presented and discussed from several points of view: Historical antecedents, assessment of the dependent variable, internal and external validity and pre-experimental vs experimental single-case designs. In addition, general characteristics of experimental single-case designs are presented along with examples of the most common design types. Visual inspection as well as statistical methods for the evaluation of data are presented. It is argued that single-case experimental designs are well suited for medical research as well as clinical practice. They provide tools for testing causal hypotheses concerning the effects of interventions in the single case.