The rationale behind the method of estimating the operating characteristics of discrete item responses when the test information of the Old Test is not constant was presented previously. In the present study, two subtests of the Old Test, i.e. Subtests 1, and 2, each of which has a different non-constant test information function, are used in place of the Old Test, and the item characteristic functions of ten hypothetical binary items are estimated on the simulated data of five hundred hypothetical examinees, using Simple Sum Procedure of the Conditional Probability Density Function (PDF) Approach and the Normal Approach Method. The research is designed to test the method as well as to examine the possibility of reducing the number of test items in the Old Test. The reduction of the number of test items from 35 in the original Old Test to 25 in both Subtests 1 and 2 proved to be acceptable. It was suggested from the results that even a smaller number of test items in the Old Test than 25 are probably needed. (Author/RL)