Standardization is the activity of normalizing norms and rules which are in general obligatory for products, services and methods of measurement, control and testing. One of the main demands to the methods of analysis is to ensure a certain level of accuracy. Requirements for the analysis sequence and the accuracy of the measurement data are the result of a compromise between the consumer and the supplier of the analysis. It is suggested to use functional-target analysis in order to determine the relations between the properties and functions of the object. On the example of X-ray fluorescence analysis it is shown that it is possible to formulate the functions of the researched object and analyze the properties which are necessary to put these functions into practice. It allows for determining such indicators of the analytical method that can be assessed quantitatively. Such approach can be used to construct mathematical models to estimate the degree of accuracy required for solving specific problems of consumers of precise measurement information.