(eng): The comparison of two groups of decision-making units (DMUs) has been already subject of scientific reflection. So far, some statistical tests have been developed. This article addresses estimating the difference between expected outputs of two groups of DMUs. In contrast to other efficiency evaluation methods, this publication focuses on quantitative assessment of this difference, not on the hypothesis testing. The article focuses on single output DMUs and the designed statistical tests are examined on various simulated data sets as well as on one realworld example. Some of them stem from the data envelopment analysis, others are related to the local regression.