ENThe aim of this article is to propose a methodology to determine an appropriate period for the quantitative evaluation of the development of SER as a process and to validate it using a real-world example. There has been an increasing the analysis and assessment of the state of socio-economic systems (SES) for the purpose of managing their targeted development are gaining importance. The adequacy of such analysis and assessment is largely dependent on the duration of the period under consideration. Recently, the analysis and assessment of the state of socioeconomic systems (SES) for the purpose of managing their targeted development have gained importance. The accuracy of such analysis and assessment depends a lot on the duration of the period under consideration. In the absence of a clearly defined period, time spans of varying durations are used, ranging from a few years to several decades. The determination of an appropriate period is based on the impact of past development periods (years) on recent years. Studies have shown that this influence is strong (r = 0.85–0.95) and can be described using both linear and nonlinear regression models. The appropriate analysis period can be identified on the basis of the selected correlation coefficient between the most recent (base) year and the development observed in the preceding years. The optimal analysis period, expressed in years, corresponds to the point at which this relationship remains statistically significant. Keywords: socio-economic systems, development, analysis period.