Monthly gold prices. Refer to the monthly gold prices, Exercise 14.31 (p. 14-24). Two models were used to forecast the monthly 2019 gold prices: an exponential smoothing model with w = .5 and a Holt model with w = .5 and v = .5.

a. Use MAD, MAPE, and RMSE criteria to evaluate the two models’ accuracy for forecasting the monthly 2019 values using the 2015–2018 data.

b. Use the MAD, MAPE, and RMSE criteria to evaluate the two models’ accuracy when making the one-stepahead forecasts, updating the models with each month’s actual value before forecasting the next month’s value.