19. Use Holt-Winter's additive method to create a seasonal model that minimizes the MSE for the data set. Use Solver to determine the optimal values of a, , and y. a. What are the optimal values of a, , and y? b. Prepare a line graph comparing the predictions from this method against the original data. c. What are the forecasts for each of the next 6 months using this technique? 20. Use Holt-Winter's multiplicative method to create a seasonal model that minimizes the MSE for the data set. Use Solver to determine the optimal values of , B, and y. a. What are the optimal values of a, , and y? b. Prepare a line graph comparing the predictions from this method against the original data. c. What are the forecasts for each of the next 6 months using this technique? 21. Use regression analysis to fit an additive seasonal model with linear trend to the data set. a. What is the estimated regression function? b. Interpret the R value for your model. c. Interpret the parameter estimates corresponding to the indicator variables in your model. d. Prepare a line graph comparing the linear trend predictions against the original data. e. What are the forecasts for each of the next 6 months using this technique? Time Year Month Period COGS 1 12 1 21637 2 2 25506 3 3 26594 4 4 21933 5 5 23117 6 26979 7 7 28337 8 8 28926 9 9 25015 10 10 28196 11 11 24170 12 12 25004 2 1 13 24575 2 14 35848 3 15 35217 4 16 32759 5 17 36542 6 18 36109 7 19 40279 8 20 37816 9 21 36338 10 22 37814 11 23 39359 12 24 34151 3 1 25 39862 2 26 50664 3 27 48533 4 28 45382 5 29 43981 6 30 41276 7 31 44284 8 32 46920 9 33 47469 10 34 43187