I was wondering if there was a simple way to predict future sales based on past sales? I know the 'forecast' procedure exists but my version of SAS does not have the ETS license. Is there an alternative that exists in the base version?
" Excel will readily fit a Trend Line to the series. The forecaster needs to be aware however that the Trend Line is calculated by giving equal weight to all the data-the distant past is given as much weight as the recent past. So despite that trends change over time, the Trend Line does not adapt very fast and can produce outdated forecasts. Perhaps that is why the Trend Line was the least accurate of two-dozen extrapolative procedures compared in the famous M-Competition. Excel's Trend Line is be avoided for time series forecasting. Better to replace it with Exponential Smoothing procedures."