What characterizes a single-subject design?

The characterization of a single-subject design is centered around the examination of the effects of an intervention on a single subject over time. This design is particularly useful in applied behavior analysis as it allows for the continual monitoring of an individual’s behavior across different phases or conditions. By focusing on one subject, researchers can identify variability in behavior that might not be detectable in group studies.

In addition, the repetitive measurement of the same subject under different conditions enhances the reliability of the findings, as changes in behavior can be directly linked to the intervention rather than being influenced by group dynamics or external variables that might affect multiple subjects. This design is also flexible and can be adapted for various types of assessments and interventions, making it a powerful tool in both clinical and research settings.

The other options do not align with the key principles of single-subject design. For instance, studying multiple subjects or using control groups diverges from the single-subject focus, and an exclusive emphasis on observational data may not capture the intervention's direct impact on behavior over time.