The last 4 weekly values of sales were 80,100,105 and 90 units. The last 4 forecast (for the same 4 weeks) were 60, 80, 95 and 75 units.
Calculate the MAD, MSE and MAPE for these 4 weeks
Sales - 80, 100, 105, 90
Forecast - 60, 80, 95 75
Error - 20, 20, 10, 15
Error Squared - 400, 400, 100, 225
PCT Error - . 25, .20, .095, .167