A comparative study of Rasch and Ziller's models of item analysis

This study compared Rasch and Zillers models in relation to item and person parameters on one hand and guessing tendency on the other. The conditions under which the two models can effectively be applied were highlighted. Based on these conditions, the two models were then compared in line with the various parameters being estimated. It was then concluded that the tendency of a testee to guess (under Ziller's model) is a function of the ability of the testee and the difficulty level of the test items. Similarly, the probability of a correct response to an item (under Rasch Model) is also a function of the difficulty level of that test and the ability of the person responding to the item. This justifies the inter-relationship between Rasch and Ziller's models. African Journal of Educational Studies in Mathematics and Sciences Vol. 1, 2001: 45-51