Effect of Item Parameter Drift in Mixed Format Common Items on Test Equating

Abstract

The aim of the study was to examine the common items in the mixed format (e.g., multiple-choices and essay items) contain parameter drifts in the test equating processes performed with the common item non-equivalent groups design. In this study, which was carried out using Monte Carlo simulation with a fully crossed design, the factors of test length (30 and 50), sample size (1000 and 3000), common item ratio (30 and 40%), ratio of items with item parameter drift (IPD) in common items (20 and 30%), location of common items in tests (at the beginning, randomly distributed, and at the end) and IPD size in multiple-choice items (low [0.2] and high [1.0]) were studied. Four test forms were created, and two test forms do not contain parameter drifts. After the parameter drift was performed on the first of the other two test forms, the parameter drift was again performed on the second test form. Test equating results were compared using the root mean squared error (RMSE) value. As a result of the research, ratio of items with IPD in common items, IPD size in multiple-choice items, common item ratio, sample size and test length on equating errors were found to be significant.

Equating of standardized science subjects tests using various methods: which is the most profitable?

“…Two methods are included in the separate calibration method: the moment method and the graphic method (Bramley, 2020). At least three methods can be used for the moment method, namely the Mean -Sigma method and the Mean-Maen method (Uysal et al, 2022). Two methods can be used in the graphical method: the characteristic curve method from Haebara and the characteristic curve method from Stocking & Lord.…”