Efficiency of information systems and technologies: features of estimation

The task of creating a methodology for evaluating the efficiency of information systems and technologies is considered. A distinctive feature of information systems is their service nature which results in the need of indirect estimation of their efficiency through terminal positive effect of metasystem, for the benefit of which this system was created or adapted.
The brief summary of the existing approaches and techniques for estimating efficiency of information systems and technologies is provided. Ambiguity of the used efficiency measurements, resulting in the difficulties of the creation of a formalized, numerical technique for efficiency estimation, was revealed.
The quantitative efficiency evaluations of an information system, which take into account the probabilistic nature of the basic data used for creation of these estimates, are offered. The options of necessary and sufficient criteria for efficiency of information systems, expressed through efficiency of metasystems for the benefit of which they function, are provided.