Seminar in Psychometrics
Item Response Theory Equating Methods for Multiple Forms
Date and time: April 14, 2021 (3:40 PM CET)
Place ICS CAS room 318, Pod Vodárenskou věží 2, Prague 8, also on Zoom.
Abstract. Many testing programs use multiple forms of a test to deal with the security issues connected to test disclosure. However, since each form is composed of different items, the test scores are not comparable. To overcome this issue, it is possible to apply the statistical procedure of equating. This talk focuses on Item Response Theory (IRT) equating methods for the common-item nonequivalent group design. Under this design, the forms have a set of items in common and they are administered to different groups of examinees. The equating process consists in the conversion of the item parameter estimates to a common scale using a linear transformation, and the determination of comparable test scores. The coefficients of this linear function are called equating coefficients. Despite many testing programs use several forms of a test, the equating methods proposed in the literature mainly consider only two test forms. In this talk, the equating methods for two test forms will be reviewed and some newer methods for equating multiple test forms will be presented. The methods will be illustrated using the R packages equateIRT and equateMultiple.
