How many participants are required for high-quality single subject design studies?

In high-quality single subject design studies, the focus is primarily on the individual participant rather than on a large sample size, which is more typical in group-based designs. The answer indicating at least 20 participants reflects a balance: it is large enough to ensure that there can be variability in responses to interventions and increases the generalizability of the findings across different individual cases.

Single subject designs often involve repeated measures on the same participant to understand the effectiveness of an intervention over time. While they can be conducted with fewer participants, having at least 20 allows for a more robust analysis and helps in identifying patterns or trends that might otherwise be overlooked if the sample size were too small. This number also provides a practical compromise that facilitates the examination of individual variability within the context of a more extensive investigation.

In contrast, options indicating significantly higher participant numbers, or those suggesting only one investigator’s participants, do not align with the principles of single subject design, which values detailed observations of individual cases rather than broad statistical comparisons across large groups. This specificity allows for richer, more contextually relevant data on how individuals respond to certain educational interventions.