  The main approaches for the formation of generalized conclusions about
operation quality of complex hierarchical network systems are analized.
Advantages and drawbacks of the "weakest" element method and a weighted linear
aggregation method are determined. Nonlinear aggregation method is proposed for
evaluating the quality of the systems, which consist of elements of the same
priority. Hybrid approaches to form generalized conclusions are developed based
on the main aggregation methods. It is shown that they allow to obtain more
reliable aggregation results.
