Rasch Measurement and Item Banking: Theory and Practice.

The Rasch Model is an item response theory, one parameter model developed that states that the probability of a correct response on a test is a function of the difficulty of the item and the ability of the candidate. Item banking is useful for language testing. The Rasch Model provides estimates of item difficulties that are meaningful, irrespective of the ability level tested. This paper focuses mainly on how the model can contribute to the feasibility of item banking in terms of language testing. The present research deals mainly with the following basic aspects of item banking: calibration of items for storage; the measurement of student abilities; and the advantages and limitations of item banking. Item characteristics can be determined either by traditional item statistics (Classical Test Theory) or a newer method of estimating item statistics called Item Response Theory. In this paper, Item Response Theory is used for dealing with item characteristics. The sample data for the research in this paper were taken from a multiple choice test that consisted of 10 items and was given to 105 students. It is concluded that Item Response Theory facilitates item banking by allowing all of the items to be calibrated and positioned on the same latent continuum by means of a common metric, and allows additional items to be added subsequently without the need to locate and retest the original sample of examinees. Furthermore, an item bank permits the construction of tests of known reliability and validity based on appropriate selection of item subsets from the bank without further need for trial in the field. (Contains 12 references.) (KFT) Reproductions supplied by EDRS are the best that can be made from the original document. Rasch Measurement and Item Banking : Theory and Practice PERMISSION TO REPRODUCE AND DISSEMINATE THIS MATERIAL HAS BEEN GRANTED BY IALKI N-eA&YY)UP0,-, 1 TO THE EDUCATIONAL RESOURCES INFORMATION CENTER (ERIC) Yuji Nakamura U S. DEPARTMENT OF EDUCATION Office of Educational Research and Improvement EDUCATIONAL RESOURCES INFORMATION /CENTER (ERIC) This document has been reproduced as received from the person or organization originating it. 0 Minor changes have been made to improve reproduction quality. Points of view or opinions stated in this document do not necessarily represent official OERI position or policy. 15 Ma1011 (2001 *10 )) 2 BEST COPY AVAILABLE Rasch Measurement and Item Banking : Theory and Practice