The analysis of the state and prospects of development of reference base and basic approaches used for the measurement uncertainty evaluation in test and calibrating laboratories was conducted. The methods of realization of model approach are analysed through the law of uncertainty distribution and law of distribution propagation. Approaches of uncertainty contributions estimation are resulted by the coefficients of sensitiveness, by the method of partial increments, methods of reduction and transformation. The analysis of basic methods of expended uncertainty estimation is conducted. The methods of realization of empiric approach are analysed by the results of laboratory and interlaboratory tests.
standard uncertainty, expended uncertainty, model approach, empiric approach