Forecasting Exercise: Double Exponential Smoothing a. Given the following demand data and the parameters (highlighted), calculate FITt for periods 1 to 9 by using the double exponential smoothing method. b. Using your last Ft and Tt, forecast demand for periods 10, 15, and 20. c. Assess the accuracy of your forecasts using CFE, bias, MAD, and MAPE. Formulas: 1. FITt = Ft + Tt 2. Ft = FITt-1 + a(At-1 - FITt-1) 3. Tt = Tt-1 + B(Ft - Ft-1 Tt-1) (OR: T+ = Tt-1 + aB(At-1 FITt-1)) 4. FITtn = Ft+1 + n x Tt+1 (e.g. t is the last period with actual demand, when t=8, n = 2, FIT8+2 = F8+1 + 2 x T8+1) Period At Ft Tt FITt E rror ABS|EL %[EL Parameters: 120 100.00 10.00 alpha = 0.4 136 beta = 0.25 143 F1 = 100 158 T1 = 163 172 Accuracy: 185 CFE = =SUM(Errors for all periods) 192 Avg Error = =AVG(Errors for all periods) MAD = =AVG(Errors| for all periods) MAPE= =AVG(ERRORt|/At for all periods) * 100% 10