Single-subject Experimental Designs as a Useful Tool for Demonstrating Intervention Effects in Neurorehabilitation : Part 2. Types of Study Designs and Visual Analysis of Their Results

A single-subject experimental design (SSED) involves gathering individual data from a small group of patients to assess intervention effects. It enables the investigation of new therapeutic approaches or specific protocols, even for those less familiar with research processes, thereby facilitating high-quality studies. However, due to the nature of SSED, which involves a small number of participants and presents outcomes through repeated measurements of intervention effects, concerns about threats to the validity of the research may arise. Consequently, recent efforts have focused on minimizing these threats, and the criteria for evaluating the quality of SSED studies are becoming more clearly defined. Well-designed SSED studies can provide reproducible results in neurorehabilitation and significantly contribute to expanding knowledge of intervention effects by helping to explore the feasibility of clinical interventions and advance research. This serves as a fundamental basis for promoting the development of neurorehabilitation. In the field of neurorehabilitation, frequently used SSEDs include reversal designs, alternating deigns, multiple baseline designs, changing criterion designs, and others. Visual analysis has mainly been used to represent SSED results, which include the mean level, trend, and variation of data in the baseline and intervention phases. To support the understanding of research outcomes, such detailed information needs to clarify more appropriate study protocols and describe their results in neurorehabilitation. Accordingly, this study aimed to present various types of SSED studies and introduce visual analysis methods to represent their findings, with the goal of promoting the adoption of the SSED research methodology in neurorehabilitation, thereby enhancing the integration of therapeutic evidence into clinical practice.