Abstract:

Test vertical equating refers to transforming the performance of students in tests of various levels to the same scale. Item Response Theory (IRT) and Multidimensional Item Response Theory (MIRT) are the main methods used in vertical equating. IRT method is an effective way to build a vertical scale because IRT models impose no requirement on the distribution of test-takers’ ability and that item parameters are independent of the samples. However, its application is restricted when the test dose not satisfy the unidimensional assumption. MIRT is a combination of IRT and factor analysis, making it an important tool in vertical equating to estimate ability parameter and item parameter precisely in multidimensional test. Current researches focus on the applicability of IRT and MIRT, calibration method and parameter estimation method in vertical equating and comparison study of the two methods. Future studies should concentrate on including more variables when comparing IRT and MIRT in order to expand their applications.

Key words: item response theory, multidimensional item response theory, vertical equating