How practitioners (and others) can make scientifically viable contributions to clinical-outcome research using the single-case time-series design.

Although clinicians typically possess considerable interest in research, especially about which interventions do and do not work, all too often they dismiss the notion that they themselves can make viable scientific contributions to the outcome literature. This derives from an unfortunate assumption that the only true experiment is a between-groups experiment. There is another form of true experiment that is perfectly compatible with real-world clinical practice: the single-case time-series design. Intensive and systematic tracking of one or a few patients over time can yield viable inferences about efficacy, effectiveness, and, under some circumstances, mechanism of change. This paper describes how clinicians working with hypnosis can carry out such research. The rationale and essential features of time-series studies are outlined; each design is illustrated with actual studies from the hypnosis literature; and new methods of statistical analysis, well within the statistical competence of practitioners, are described.