Like the Iowa Assessments™, CogAT's foundation has always been its strong research base. Dr. Lohman is one of the leading researchers in the field. Click here to see some of his research work. This emphasis on basis figures prominently in the development of CogAT itself.
Before an item even makes it onto a form for a research event, it is first reviewed by our authors and by HMH staff for appropriateness. After this review, each item is carefully analyzed by a panel of Bias and Fairness reviewers, a heterogeneous group of educators across the country. This panel ensures that each item neither advantages nor disadvantages any particular cultural group. After an item has passed these reviews, it goes out for field tryout. Statistics from each item are analyzed to determine if it discriminates well, and for what and at what age or grade's test it is appropriate. Finally, test forms are assembled from these items that have been validated for a national standardization.
Dr. Lohman and HMH's staff of psychometricians carefully construct a robust sample of students that reflects the larger demographic makeup of the current U.S. school-age population, conduct large-scale studies, then carefully analyze data to create sound statistics. These statistics are at the core of the reliable comparisons that the tests offer.
In the fall of 2010, HMH coordinated a major standardization event for the new Form 7 of CogAT. There were several mini-studies incorporated in the larger effort that linked the new Form 7 with previous CogAT forms and other HMH assessments. However, the primary purpose of the standardization event was to provide updated national norms for Grades 1–12 of the new form.
The foundation of the standardization lies in the sampling plan. Samples of schools were selected using a stratified random sampling process to develop a national probability sample, representative of students nationwide. Three stratifying variables were used to classify school districts throughout the nation: geographic region, district enrollment, and an index of the socioeconomic status (SES) of the school district. Although a stratified random sampling process was used to select the sample of schools, weighting adjusted the final obtained samples back to the targets used in the sampling.
The results of these standardization events will allow future users of the new CogAT, Form 7 to have up-to-date relative comparisons to guide interpretations of student performance.