Time series smoothing
Also, see Figures 4.8 and 4.9 (text p. 145) for an illustration of how the weights decay for different values of a and an example of single exponential smoothing of strictly random data respectively
In addition, see Figures 4.10 and 4.11 (text p. 146) for how single exponentially smoothed data lags behind demand for trend and seasonal scenarios (as expected since it’s a type of WMA methodology)