Our approach to forecasting seasonal data is based on the classical decomposition method developed by economists in the nineteenth century. ;Decomposition means separation of the time series into its component parts. ;A complete decomposition separates the time series into four components: ;seasonality, trend, cycle, and randomness. ;The cycle is a long range pattern related to the growth and decline of industries or the economy as a whole.
Two worksheets are available for seasonal adjustment. ;MULTIMON uses the ratio-to-moving average method to adjust monthly data. ;ADDITMON uses a similar method called ;the difference-to-moving average method to adjust monthly data. ;It may be necessary to test both of these worksheets before choosing a seasonal pattern.
Operations Manager - Saver Package contains many business Excel spreadsheets: forecasting, production planning, inventory management, job scheduling, quality control, analysis of waiting lines, and more.
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