6.
Process or Product Monitoring and Control
6.4. Introduction to Time Series Analysis


Exponential smoothing schemes weight past observations using exponentially decreasing weights 
This is a very popular scheme to produce a smoothed Time Series.
Whereas in Single Moving Averages the past observations are
weighted equally, Exponential Smoothing assigns exponentially
decreasing weights as the observation get older.
In other words, recent observations are given relatively more weight in forecasting than the older observations. In the case of moving averages, the weights assigned to the observations are the same and are equal to 1/N. In exponential smoothing, however, there are one or more smoothing parameters to be determined (or estimated) and these choices determine the weights assigned to the observations. Single, double and triple Exponential Smoothing will be described in this section. 