Experimental intervention research on students with learning disabilities: A meta-analysis of treatment outcomes

This article summarizes a comprehensive synthesis of experimental intervention studies that have included students with learning disabilities. Effect sizes for 180 intervention studies were analyzed across instructional domains, sample characteristics, intervention parameters, methodological procedures, and article characteristics. The overall mean effect size of instructional intervention was positive and of high magnitude (M = 0.79). Effect sizer were more positive for a combined model that included components of direct and strategy instruction than for competing models. Interventions that included instructional components related to controlling task difficulty, small interactive groups, and directed responses and questioning of students were significant predictors of effect size, and interventions that varied from control conditions in terms of setting, teacher and number of instructional steps yielded larger effect sizes than studies that failed to control for such variations. The results are supportive of the pervasive influence of cognitive strategy and direct instruction models for remediating the academic difficulties for children with learning disabilities.