The Bee Line Caf is well known for its popular homemade ice cream, which it makes in a small plant in back of the cafe.

The Bee Line Café is well known for its popular homemade ice cream, which it makes in a small plant in back of the cafe. People drive long distances to buy the ice cream. The two ladies who own the café 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 café. They have accumulated the following sales records for their ice cream for the past 12 quarters:

Year/Quarter Ice Cream Sales (gal)
2008: 1 ..................350
2...................510
3 ..................750
4 ..................420
2009: 5...................370
6 ..................480
7 ...............860
8 ...............500
2010: 9 ..................450
10 ................550
11 ................820
12 ................570
Develop an adjusted exponential smoothing model with α = 0.50 and β = 0.50 to forecast demand, and assess its accuracy using cumulative error (E) and average error (Eˉ). Does there appear to be any bias in the forecast?