In this study, it was aimed to check the statistical equivalence of OKS test edition applied in different years. The data of the study was collected from 1030 8th grade students from various secondary schools. Single group design and linear equating procedure from classical equating methodologies were used in the study. At the same time, as a part of the equating process, SEEs (Standart error of equating) for single group were estimated. Confidence bands based on the SEE were used to assess equivalence of OKS test edition. As a result of the study, differences were found between equating function and identity function, differences ranging from -0,14 to 0,833. Because these differences are more than two SEEs for some score range, the two OKS test edition applied 2003 and 2005 can not be considered equivalent and interchangeable.