What these and other research suggest is that focusing only on large sample studies and the use of average change scores calls into question the usefulness of current patient-centered treatments. As noted by Dr. Turk, when data are averaged, various pain syndromes, drugs, surgical procedures, and studies in different countries are often included, which may mask the efficacy results of different treatments with Different samples. Single case methodology could be one of the ways to overcome these limitations. The single case investigation is a type of experimental study that offers experimental control within a single case.