A simple forecasting method for weekly sales of flash drives used by a local computer dealer is to

form the average of the two most recent sales figures. Suppose sales for the drives for the past $12$

weeks were

a$.$ Determine the one$-$step$-$ahead forecasts made for periods $3$ through $12$ using this method.

b$.$ Determine the forecast errors for these periods.

c$.$ Compute the MAD, and the MSE based on the forecast errors computed in part $($b$).$

$3.$ Two forecasting methods have been used to evaluate the same economic time series. The results are

Compare the effectiveness of these methods by computing MSE and MAD. Do each of the measures of

forecasting accuracy indicate that the same forecasting technique is best? Explain.