Forecasting Methods, Models, Techniques
The forecasting method you select is a function of multiple qualities about your item. Is demand steady, cyclical or sporadic? Are there seasonal trends? Are trends strong or limited? Is the item new? Each item being forecast has a somewhat unique history (and future), and therefore an optimal method. A method that accurately forecasts one data set might prove inaccurate for another.
Determining the optimal forecast method is a rather complex science, especially across a large product line. This may be nearly impossible using only spreadsheets. However, sophisticated forecasting software can within seconds test multiple methods for each item to determine which method will give you the most accurate results.