Sensitivity analysis in Data Envelopment Analysis (DEA) is studied for perturbations of data for which ranking of efficient Decision Making Units (DMUs) is preserved. Sufficient conditions for efficient DMUs to preserve their ranks under the perturbations of data are achieved. Accordingly, it can be found out how to change outputs or inputs of an efficient DMU while preserving ranking of all efficient DMUs. In addition, an illustrative numerical example is provided to receive a better comprehension. تفاصيل المقالة