Investigation of unidimensionality examination methods in the framework of CTT in terms of various variables

The aim of this study is to examine the concept of unidimensionality, which is an important concept in measurement science, and to examine and evaluate the KR-20, Omega and Eigenvalue Ratio indices used in unidimensionality studies within the framework of CTT. For this purpose, data was generated according to various factors (sample size, number of items, interdimensional correlation and factor loading average). Data generation and analysis was carried out using the version of R Program 4.2.3. The produced data were examined according to the average indexes of KR-20, Omega and Eigenvalue Ratio, and the ratios of the results obtained were tabulated and visualized with multifaceted graphing. Analysis and graphing processes were carried out through the program written by the researcher. According to different conversion criteria, the average values of KR-20, Omega and Eigenvalue Ratio coefficients were calculated and compared. The average values of KR 20, one of the reliability-based methods for unidimensionality analysis, and Omega indexes, one of the factor analysis-based methods, were very close to each other in all changes. The average value of the Eigenvalue Ratio was most affected by the various conditions. When it is desired to obtain more sensitive results under changing conditions for unidimensionality, it may be recommended to use the Eigenvalue Ratio index, which is an index based on principal components.