Since May of 2005, the purchase manager at a department store has been using a 4-period moving average to forecast sales in upcoming months. Sales data for the months of January through July are given in the table below.
|
Month
|
Sales
|
|
Jan
|
65
|
|
Feb
|
65
|
|
Mar
|
41
|
|
Apr
|
50
|
|
May
|
63
|
|
Jun
|
38
|
|
Jul
|
72
|
Compute the mean absolute deviation (MAD) for the four-period moving average forecasts. The forecast values are calculated with an accuracy of two decimal digits. Specify the MAD as a whole number by rounding.