Biasedness of forecast errors : an intermittent demand perspective

In the article it is claimed that certain ex post forecast errors demonstrate such a property as biasedness. A definition of forecast error biasedness is proposed and discussed. In the theoretical part, the most popular forecast errors, including errors useful in intermittent demand forecasting, are analyzed with regard to their biasedness. In the empirical part, properties of the considered forecast errors are verified for real intermittent demand time series. Forecasts are obtained, inter alia, by means of Croston's and TSB methods. In the conclusions unbiased forecast errors are emphasized. Furthermore, the best forecast errors for intermittent demand data are proposed. The presented considerations, aside from the theoretical part, might support decision systems in enterprises dealing with intermittent demand forecasting, such as distribution centers, warehouse centers etc.