The Effect of Alternatives Number and Changing the Position of the Strong Distractor on Items Parameters, Person Ability and Information Function

Abstract

This study aimed at verifying the effect of the number of alternatives and changing the strong distractor position on the items parameters, person’s ability and information function. To achieve this aim, a 41 item multiple – choice achievement test in 10^th grade mathematics was constructed.The test had four different forms according to number of alternative and the strong distractor position. The responses of 2111 examinees on the four forms were analyzed by Bilog–Mg3 programs according to the three parameter logistic model. The results of two-way ANOVA revealed no significant statistical differences between the means of item difficulty and guessing parameters. Differences were found, however, between the means of item discrimination, due to the position of the strong distractor; the differences were in favor of the second form. No differences were found in the means person’s ability parameter, but the information function of the test varied due to the test forms. Significant differences were noticed in the values of empirical reliability coefficients in favor of the second form.