The study attempts to forecast the total costs of a company in Poland. The first stage of the research was analyzing and evaluating the time series of total costs. It detected: trends, seasonality and a random factor. This became a premise for the application of two methods for forecasting: Holt-Winters’ multiplicative and additive. The research shows that the Holt-Winters’ multiplicative model proved to be better in forecasting total costs in the research subject. The forecasted total costs from July to December 2022 will reach PLN 45 395 685, while from January to December 2023, their value will amount to PLN 85 948 927.
The multidimensional comparative analysis and the forecasting of minimum salaries in 21 European countries were conducted in the study. The research began with the ranking of the data, the amount of salary rates taken as a basis, the rise expressed in euro and the values of dynamics indices on a constant base. Then the data was aggregated. The time series of the lowest salaries in 21 European countries was analyzed and evaluated. Thus, regularities were observed that were used to select the Holt-Winters’ exponential smoothing method for the forecasting of these salaries. The obtained forecasts were analyzed and evaluated with the use of indices, such as forecasting errors.