1) Given the following period data which of the following would be the correct Mean Absolute Deviation (MAD)?

Period 1 the demand is 141, the forecast is 138, the absolute value of the error term is 3, the absolute value of the error term squared is 9 and the absolute percentage error is 0.0213;

Period 2 the demand is 138, the forecast is 139, the absolute value of the error term is 1, the absolute value of the error term squared is 1 and the absolute percentage error is 1/138=0.0072;

Period 3 the demand is 144, the forecast is 148, the absolute value of the error term is 4, the absolute value of the error term squared is 16 and the absolute percentage error is .0278;

Period 4 the demand is 150, the forecast is 145, the absolute value of the error term is 5, the absolute value of the error term squared is 25 and the percentage error is 5/150=0.0333;

Period 5 the demand is 146, the forecast is 150, the absolute value of the error term is 4, the absolute value of the error term squared is 16 and the absolute percentage error is 4/146=.0274.

2.8

3.4

2.6

3.2

2) Using the data provided, which of the following would be the correct demand forecast of the demand for month 5 using the nave (last data point forecasting method)?

Data: Month 1 132, Month 2 137, Month 3 138, Month 4 141

132

141

138

137

3)Using the data provided and assuming the demand for month 13 was actually 144 which of the following would be the correct demand forecast for month 14 using the weighted MA(3) forecasting method with weights of 0.5, 0.3, and 0.2 where 0.5 is the weight applied to the most recent months demand?

Data:

Month 1 135, Month 2 142, Month 3 131,

Month 4 132, Month 5 140, Month 6 137,

Month 7 150, Month 8 140, Month 9 132,

Month 10 137, Month 11 138, Month 12 141,

Month 13 144.

143.6

144.5

144.9

141.9