Analysis of psychometric properties of the developed general ability test according to classical test theory and item responce theory

In this study, a general ability test development process was conducted for children aged 12-13 and psychometric properties of the test were examined according to classical test theory (CTT) and item response theory (IRT). The aim of the test was developed to make educational decisions about individuals and to guide them according to their abilities. This is a basic research study, using the test development process of Crocker and Algina to meet the requirements of both theories. The descriptive information and item samples of Stanford-Binet and Weschler scales, which aim to measure the ability factors of Cattell-Horn-Carroll theory, were determined and target measurement/competence expressions were determined. In order to ensure the content validity of the test, expert opinions were used both in the determination of target measurement/competence expressions and in the process of writing the items; also, tables of specifications were prepared. 24 multiple choice items were written in the trial forms to measure each target measurement/competence statement. The pilot application was carried out by using stratified sampling method with 1411 students in the 5th and 6th grades and the final application with 642 students. With the analysis of the obtained data, item statistics were calculated according to the CTT and item parameters predicted according to IRT, item information function was evaluated and the final test was formed by selecting 96 items that required both theories. The data obtained from the test was analyzed by using ITEMAN and IRTPRO programs. Before the psychometric properties of the developed general ability test were determined, the assumptions about the theories were examined, the data obtained showed normal distribution characteristics, and the structure of the sub-tests was unidimensional and therefore local independent. The reliability of the developed test was examined according to both theories. The reliability of the test according to CTT was examined with KR-20 reliability coefficient. Verbal, numerical, visual-spatial ability subtests and KR-20 reliability coefficients obtained from all items were calculated as 0.84, 0.90, 0.85 and 0.94, respectively. The reliability of the scale according to IRT test and item information functions were examined. When the test information function values are examined, it is seen that the subtests provide more information for the medium skill levels and that the measurement is done with low errors. The marginal reliability coefficient was found to be quite high and it was concluded that the subtest scores were reliable. As a result, statistical analysis revealed that it is a test with psychometric properties that can be used to determine the general ability levels of 12-13 years old children.