Calibration of the fuzzy model involves tuning the adopted parameters that define the membership functions of input vari- ables and the position of singletons, adjoined to the output variable and definition of fuzzy rules set. In other words, training of the fuzzy evaluation model implies selection of a large number of parameters. Each of the specified membership functions for linguistic variables has at least two parameters, and there are 10 such functions. Also, 10 singletons take part in the definition of the output variable and their positions need to be selected too.