Features of the “Fourier Analysis” Option in the Excel Spreadsheet When Performing Spectral Analysis and Identifying Periodic Patterns in the Time Series of Economic Indicators

Abstract

The Excel spreadsheet, which is available "at hand" for each researcher of time series of economic data, allows for their Fourier analysis, that is, to identify cycles in them, and select a functional approximation for them. However, it does this using the FFT algorithm. The FFT algorithm is not familiar to a wide range of users who are not too sophisticated in higher mathematics – economists, merchants, managers, engineers. This work is addressed to them, the purpose of which is to teach how to use this option for spectral analysis and to identify periodic patterns in the time series of economic indicators. The peculiarity of using Excel is that the result of the calculation using the "Fourier Analysis" option is issued in an "encrypted" form, which may be understandable for a mathematician, but for a researcher of economic indicators is completely incomprehensible. In this paper, the sequential decryption of the operation of the option is carried out by communicating with it and asking it questions, the answers to which we already know. As a result, an algorithm for decrypting the option response is obtained. and an algorithm for constructing a functional type of periodic patterns. Thus, there is a possibility of forecasting not only on the basis of a trend model, but also much deeper - taking into account the identified periodicities. The algorithm of such forecasting is also given.