Benford's law of the "first digits" states that in spite of intuitively expected equal frequency of 1/9 of the decimal digits r = 1, ... , 9 appearance on the first place of any number, various empirical studies show another pattern of these frequencies distribution, which is log[subscript 10](1 + 1/r). The article considers this law and other designs of data generation for pair comparison matrices, and several estimation techniques for the priority vectors. Among those are Analytic Hierarchy Process (AHP), Simple Multi-Attribute Rating Technique (SMART), and several additional approaches of the multiple criteria decision making. The closeness of a priority vector evaluated by a data elicited from an expert to one or another pattern helps to identify a nature of the data comparison process. (Contains 1 table and 1 figure.)