A forecasting method has produced the following data over the past 4 months shown in the data set. (total of 4 marks) a. Calculate the mean absolute deviation (MAD) for the 4 months. (show the details of your calculations) (2 marks) b. Calculate the mean absolute percentage error (MAPE) for the 4 months. (show the details of your calculations) (2 marks) Month Demand Forecast
1 120 100 2 110 130 3 150 180 4 130 160