User Guide

234
Chapter 11
Exponential Smoothing
The Exponential Smoothing procedure performs exponential smoothing of time
series data. It creates new series containing predicted values and residuals. This
topic uses t
he Inventor.sav file.
For example, you can fit a model for inventory data and use it to predict the next
week’s inventory. Suppose that for 70 days you have kept track of the inventory of
power suppl
ies and that you want to construct a model and then use it to forecast
power supplies for the next week.
To use the Exponential Smoothing procedure to forecast power supplies, follow
these step
s:
E Open the I
nventor.sav file. It is usually in the directory where SPSS is installed.
E From the m
enus choose:
Analyze
Time Series
Exponential Smoothing...
This opens
the Exponential Smoothing dialog box.
Figure 11-13
Exponential Smoothing dialog box
E Select Number of power supplies (amount) and move it to the Variables list.