The following are monthly actual and forecasted demand levels from May through December for units of a product manufactured in d company.
Month- may, june, july, august. september, october, november, december.
Actual demand - 105,82,108,112,108,114,130,120
Forcasted demand- 100,100,101,104,100,102,105,107
For the given forcast the tracking signal = ?? MAD's