Introduction to Management Science 12th Edition by Bernard Taylor

Exercise 41

For the demand data in Problem, develop a seasonally adjusted forecast for year 4. (Use a linear trend line model to develop a forecast estimate for year 4.) Which forecast model do you perceive to be more accurate: the exponential smoothing model from Problem or the seasonally adjusted forecast
Problem
The Whistle Stop Cafe in Weems, Georgia, is well known for its popular homemade ice cream, made in a small plant in back of the cafe. People drive all the way from Atlanta and Macon to buy the ice cream. The two women who own the cafe want to develop a forecasting model so they can plan their ice cream production operation and determine the number of employees they need to sell ice cream in the cafe. They have accumulated the following sales records for their ice cream for the past 12 quarters:
Develop an adjusted exponential smoothing model with =.50 and =.50 to forecast demand and assess its accuracy using cumulative error ( E ) and average error ( E ). Does there appear to be any bias in the forecast