Single-Case Design, Analysis, and Quality Assessment for Intervention Research

Abstract

Background and Purpose The purpose of this article is to describe single-case studies, and contrast them with case studies and randomized clinical trials. We will highlight current research designs, analysis techniques, and quality appraisal tools relevant for single-case rehabilitation research. Summary of Key Points Single-case studies can provide a viable alternative to large group studies such as randomized clinical trials. Single case studies involve repeated measures, and manipulation of and independent variable. They can be designed to have strong internal validity for assessing causal relationships between interventions and outcomes, and external validity for generalizability of results, particularly when the study designs incorporate replication, randomization, and multiple participants. Single case studies should not be confused with case studies/series (ie, case reports), which are reports of clinical management of one patient or a small series of patients. Recommendations for Clinical Practice When rigorously designed, single-case studies can be particularly useful experimental designs in a variety of situations, even when researcher resources are limited, studied conditions have low incidences, or when examining effects of novel or expensive interventions. Readers will be directed to examples from the published literature in which these techniques have been discussed, evaluated for quality, and implemented.

Systematic Review of Rehabilitation in Focal Dystonias: Classification and Recommendations

“…Several options exist to overcome this challenge. For example, rigorous single‐subject designs with multiple baselines, blinding, and randomization are a solution for overcoming small sample sizes in heterogeneous and rare disorders such as dystonia because they allow testing for both between‐subjects and within‐subject effects which are often masked by group level statistics . Crossover designs are another suitable option for small samples, since each person receives both the experimental and the control interventions.…”

Application of a Single-Case Research Design to Present the Effectiveness of Rehabilitation in the Clinic

“…There has been a variety of single case research designs such as (1) AB, (2) reversal, (3) multiple baseline, and (4) alternating treatment [11]. The components of a single-case research design are composed of a series of interventions and frequency of assessment in multiple phases and various conditions.…”

Using a Rocking Chair in the Care of People with Dementia: A Single-Case Research Study

“…A single-case research study (SCR) with an A-B-A design was conducted, in which the participants served as their own controls [23][24][25]. Phase A1 comprised a baseline/pre-intervention of three weeks.…”