Estimating transfer of learning for self-instructional packages across dental schools.

The most common topic of research in dental education is assessing the effectiveness of self-instructional units in various formats compared to lectures covering the same material. Generally, these studies are of high methodological quality and reveal mixed results or results slightly favoring self-instruction. All such studies, save one, have been conducted in the context of various single schools, thus confounding the effects of self-instructional format with factors particular to schools and their students. A reanalysis, using Cronbach's generalizability analysis, was performed on a study in the literature that was conducted at six schools and measured student aptitude. The reanalysis found that the largest source of variance on immediate post-test quizzes for knowledge following a three-hour unit on disturbances in tooth development was the school at which the study was conducted (24 percent), followed by student aptitude measured by DAT score (20 percent). Difference in format among lecture, booklet, and audiotape presentations accounted for 5 percent of the variance. This reanalysis demonstrated that statistically significant results from rigorous experimental designs can overrepresent what is revealed by such research. The context-specificity of educational innovations may be underestimated because few studies are replicated across schools. Studies conducted as single schools, regardless of their methodological rigor, fail to address issues associated with potential transfer of findings to other schools.