  We analyze a heterogeneity of the educational system on the basis of one
parameter: input grades of university students. We propose a mathematical model
based on the construction of universities interval order. We use the Hamming
distance to evaluate the heterogeneity of the educational system, and the
Unified State Examination (USE) scores of Russian students to illustrate the
application of the model. We show that institutions taking weak students turn
the whole system of universities into a poorly structured nonhomogeneous
system. In contrast, after deleting the weakest part, the remaining set of
universities becomes a well-structured system
