Statistical process control and rehabilitation outcome: The single-subject design reconsidered

Rehabilitation psychology embraces the scientist-practitioner model as its professional philosophy. This model's original intent was that the diagnosis and treatment of each individual case was to be regarded as a single and well-controlled experiment. Executing this ideal in rehabilitation has been problematic owing to practical, ethical, and technical concerns. Statistical process control (SPC), a robust, graphical analytic strategy developed in industry, is offered as a means to deploy single-subject designs on the front lines of rehabilitation. The history and construction of SPC control charts are presented followed by case examples relevant to rehabilitation practice (ambulation, depression, cognitive rehabilitation, agitation). SPC control charts are a time-tested, scientifically validated, and pragmatic tool to achieve and document patient outcomes.