Problem
Forecasting with a Moving Average. For a given time series of sales, the training set consists of 50 months. The first 5 months' data are shown below:
Month Sale
Sept 98 27
Oct 98 31
Nov 98 58
Dec 98 63
Jan 99 59
a. Compute the sales forecast for January 1999 based on a moving average with w = 4.
b. Compute the forecast error for the above forecast.