The aim of this study is to determine the extent to which item parameters estimated via CTT and IRT depend on group properties (being mater or non-master). Besides, the relationship between findings obtained from CTT and IRT is evaluated. The study group of this study consists of 1916 undergraduates who study at different departments (22) in educational faculty in a state university of Turkey. The relationship between item parameters obtained from datasets having different properties and the relationships between item parameters obtained via CTT and IRT have been investigated separately. Besides, the relationships between total scores for CTT and ability parameters for IRT have been examined for different datasets. The relationship between point biserial correlation obtained from CTT and a parameter obtained from 2PL is moderate and significant. It has been determined that the other relationship coefficients are low or nonsignificant. It has been determined that measurement theories estimate the ability of individuals in datasets having different distribution and properties similar. The high relationships have generally been obtained among difficulty parameters estimated from different datasets. This situation shows that the estimates obtained for CTT are group-dependent and the estimates for IRT are group-independent. Similarly, it has been observed that there is a significant difference between item discrimination indexes estimated for CTT and IRT.