My primary area of interest is computerized adaptive testing (CAT). CAT is the redesign of tests of ability, achievement, interests, personality, attitudes, preferences—or any kind of psychological variable—for delivery by computers. In a CAT, test questions (or items) are selected dynamically by psychometric algorithms programmed into the computer that identify the most efficient and effective set of items to measure each individual. The result of applying CAT is the capability of measuring each individual to a predetermined level of precision, or classifying individuals with predetermined error rates, with a minimum number of items. Most contemporary CAT procedures are based on advanced psychometric models based in item response theory (IRT). Therefore, my interests extend into methodological issues in IRT as they relate to CAT.
One of my current areas of research is the measurement of individual change. Although there has been considerable research focused on measuring change at the group level, or measuring change for an individual relative to a group, there has been virtually no research allowing the measurement of change for a single individual measured at two or more occasions on two or more variables. My research focuses on the development and evaluation of statistical tests applicable to both CATs and conventional tests for detecting psychometrically significant intraindividual change.
My second current area of research is on the effects of measurement error on the Type I error rates and power of a variety of statistical tests. Virtually all statistical tests assume error-free measurements. My research operationalizes error from an IRT perspective, allowing study of the effects of different patterns of error. Results demonstrate how measurement error deteriorates the performance of statistical tests, leading to erroneous conclusions from standard hypothesis testing and interval estimation procedures. We also are examining the differential effects of conventional tests and CATs as they result in different degrees and patterns of measurement error.
- Ph.D.: Psychology, University of Minnesota, 1963
- computerized adaptive testing
- psychometric methods
- Item response theory