Abstract:

In this research, it was aimed to compare equating errors of scale transformation methods (mean-mean (MM), mean-sigma (MS), Heabera (HB) and Stocking-Lord (SL)) in true score equating based on item response theory (IRT) under different conditions. In line with the purpose of the study, 7200 dichotomous data sets which were consistent with two and three- parameter logistic model were generated with 50 replication under the conditions of sample size (500, 1,000, 3,000, 10,000), test length (40, 50, 80), rate of the common item (20%, 30%, 40%), type of model used in parameter estimation (two and three-parameter logistic models (2PLM and 3PLM)), and ability distribution of groups (similar (N(0-1) - N(0-1)), different (N(0-1) - N(0.5,1)) for the obtained performance of methods. Common item nonequivalent groups equating design was used. R software was used for data generation and analyses. The results obtained from the study were evaluated by using equating error (RMSD) criterion. As a result of the study, considering all the conditions, it was seen that the RMSD values of the SL method were higher than the other methods, but it was seen that the MM and MS methods produced similar RMSD values. In addition, when the RMSD values of the scale transformation methods are compared, similar results are obtained in cases where 2PLM and 3PLM are used, as the sample size and test length increase, equating errors of other methods except the SL method decrease, and It was observed that the methods had lower RMSD values in cases where the common item rate is 40% and the ability distribution of the groups is similar.

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