Question 13.78

13.78 Monthly warehouse club and superstore sales.

Consider the monthly warehouse club and superstore sales series discussed in Examples 13.15 and 13.16 (pages 671–674).

club

  1. Use the moving-average approach to compute seasonal ratios and report their values.
  2. Produce and plot the seasonally adjusted series. What are your impressions of this plot?
  3. Fit a regression model based on to the seasonally adjusted series. Report the -values for the linear trend term and the quadratic trend term. Are these terms significant?
  4. Provide a forecast for sales for June 2014.