This article discusses critical issues related to conducting high-quality intervention research using experimental and quasi-experimental group designs. The importance of defining the nature of the independent variable, the value of measuring implementation, and the improvement of the quality of quasi-experiments are among the controversial topics…

This paper, a result of a series of meetings of researchers, discusses critical issues related to the conduct of high-quality intervention research in special education using experimental and quasi-experimental designs that compare outcomes for different groups of students. It stresses the need to balance design components that satisfy laboratory…