Chapter 8, Problem 23P

Cannister, Inc., specializes in the manufacture of plastic containers. The data on the monthly sales of 10-ounce shampoo bottles for the past 5 years are as follows:

1. Using the multiplicative seasonal method, calculate the monthly seasonal indices.
2. Develop a simple linear regression equation to forecast annual sales. For this regression, the dependent variable, Y, is the demand in each year and the independent variable, X, is the index for the year (i.e., $X=1$ for year 1, $X=2$ for year 2, and so on until $X=5$ for year 5).
3. Forecast the annual sales for year G by using the regression model you developed in part (b).
4. Prepare the seasonal forecast for each month by using the monthly seasonal indices calculated in part (a).