The Effect of Sample in Estimating the Information Function of the Test and its Estimating Standard Error Depending on the Modern Test Theory of Measurement

The study aims to investigate the Effect of sample size in Estimate the Information Function of the test and it’s Estimating standard Error depending on the modern test theory of measurement. To achieve the purposes of the study, responses of (7500) students from eighth grade students were are randomly selected divided into five groups (The first consist of 500 students, The second consist of 1000 students, The there'd consist of 1500 students, The fourth consist of 2000 students, and The last consist of 2500 students) subjected to the 40- item national multiple choice test for mathematics education quality adjustment. Using the Bilog-mg3 and spss programs to Estimate the Item parameters, information function, and standard Error in Estimating the information function for the five forms of the test according to three parameter logistic IRT model. The results showed that, the amount of information function estimates varies increasingly according to the increasing sample, Yet, the results show that the standard Error in estimating the information function varies decreasingly according to the increasing sample.