Science and Education Publishing Journal of Automation and Control 2372-3041 3 3 2015 12 15 Regression Analysis and Seasonal Adjustment of Time Series 118 121 EN Eva Ostertagová Department of Mathematics and Theoretical Informatics, Faculty of Electrical Engineering and Informatics, Technical University of Košice, Nemcovej 32, 042 00 Košice, Slovak Republic Oskar Ostertag AUTOMATION20153316 10.12691/automation-3-3-16 2015 7 14 2015 9 27 2015 12 13 The aim of this article is to demonstrate the dummy variables for estimation seasonal effects in a time series, to use them as inputs in a regression model for obtaining quality predictions. Model parameters were estimated using the least square method. After fitting, special tests to determine, if the model is satisfactory, were employed. The application data were analyzed using the MATLAB computer program that performs these calculations.