Experimental psychology is witnessing an increase in research on individual differences, which requires the development of new tasks that can reliably assess variations among participants. To do this, cognitive researchers need statistical methods that many researchers have not learned during their training. The lack of expertise can pose…

There has been increasing interest in applying integrative data analysis (IDA) to analyze data across multiple studies to increase sample size and statistical power. Measures of a construct are frequently not consistent across studies. This article provides a tutorial on the complex decisions that occur when conducting harmonization of measures…

Factor loadings and item discrimination parameters play a key role in scale construction. A multitude of heuristics regarding their interpretation are hardwired into practice--for example, neglecting low loadings and assigning items to exactly one scale. We challenge the common sense interpretation of these parameters by providing counterexamples…

The scores of handicapped students taking tests such as the Scholastic Aptitude Test (SAT) or the Graduate Record Examinations are flagged so that admissions officers will be aware that they were achieved under special circumstances. A series of studies was initiated to determine whether special administrations of such tests are comparable to…

The latent structure, reliability, and item discrimination of 33 items on a Centers for Disease Control (CDC) instrument representing knowledge, attitudes, and beliefs about the acquired immune deficiency syndrome (AIDS) were assessed. The study sample included 311 adolescents ranging from ages 12 to 19 years. Demographic characteristics of the…