Zuru Du Recognized for Outstanding Contributions to Modern Test Theory

New York, NY, September 2002 - Professional Examination Service (PES) is pleased to announce the selection of Zuru Du, Ph.D., Research Scientist and Assistant Director of Statistics and Scoring Services at PES, to receive the 2002 Distinguished Dissertation Award given by the American Psychological Association (APA), Division 5. The award recognizes Du for his outstanding contributions to Modern Test Theory with his dissertation entitled "Modeling Conditional Item Dependencies with a Three-Parameter Logistic Testlet Model." Du gave an address on the topic of his dissertation at an award ceremony held on August 23 at the APA's annual meeting in Chicago.

Du's dissertation presents a three-parameter logistic item response theory (IRT) model that allows for local item dependence. Standard IRT models assume that items are conditionally independent, i.e., that for an examinee at a given trait level his or her responses to any pair of items are statistically independent. This is unlikely to be true in certain situations, such as for a set of questions that are based on a medical chart or a reading passage. As well as explicating the theory behind the model, Du has developed a parameter estimation procedure and a computer program, both of which enable his model to be readily applied in practice. As many credentialing organizations consider a move toward more "authentic" assessments, Du's model provides a comprehensive solution to the problem of applying IRT to tests that incorporate related sets of questions based on real-world tasks.

When Du joined PES in 1998, he brought state-of-the-art knowledge of IRT methods to PES's Department of Statistics and Scoring Services. He has spearheaded the use of IRT methodologies to develop pre-equated examinations for PES clients. Test construction and pre-equating using IRT provide a number of benefits to program sponsors including a reduction in the waiting time between the initial administration of a new form and the release of score reports, the opportunity to select test items with optimal psychometric properties, and the capacity to build tests that most effectively fulfill their purpose. A number of PES clients are currently taking advantage of this technology, including the Association of State and Provincial Psychology Boards, the Federation of State Boards of Physical Therapy, the Human Resource Certification Institute, the National Board for Certification in Occupational Therapy, and the Pharmacy Technician Certification Board.

Du is a recipient of the 1999 Mary Catherine Ellwein Outstanding Dissertation Award given by the American Educational Research Association, Division D. His dissertation was completed in 1998 in fulfillment of the requirements for a Ph.D. in Measurement, Evaluation, and Statistics at Columbia University, New York. Du also holds Master's degrees in Applied Statistics (Columbia University) and Applied Linguistics (Hunan University, Changsha, China), as well as a Bachelor's degree in English (Hunan Institute of Education, Changsha, China). His dissertation is available through UMI at http://wwwlib.umi.com/dissertations, Du may be reached at (212) 367-4200 or at zuru@proexam.org.

PES is a nonprofit organization with 60 years' experience developing, implementing, and evaluating licensure and certification programs. PES's mission is to promote the understanding and use of sound credentialing practices by providing comprehensive services and making contributions to credentialing stakeholders in the areas of assessment practice, educational activities, scientific research, and policy development.