This paper includes a nontechnical description of methods for calculating effect sizes in intellectual and developmental disability studies. Different hypothetical studies are used to illustrate how null hypothesis significance testing (NHST) and effect size findings can result in quite different outcomes and therefore conflicting results. Whereas…

This article discusses research design problems peculiar to work with intellectually disabled subjects, such as discrepancies in uses of control groups and mental age matching, definitions of subject groups and variability within and between subject groups. Suggestions for minimizing these problems are made and alternative methodologies offered.…

This study was designed to test the hypothesis that students who are given common errors matched with correct performance as part of their instruction in carrying out a procedure will perform better than students who are given only the correct performance. The task was the procedure for correcting color imbalances in color slides, and 56 college…

More than 1,600 middle school students, including an experimental group exposed to the Biological Science Curriculum Study (BSCS), were administered the Modified Nature of Scientific Knowledge Scale. Results indicate that the students utilizing the traditional science curriculum possessed a significantly better understanding of the testable nature…