Forecasting: Practice Computational Problems Problem 1: If the forecast errors for four consecutive periods are 3, -5, 7, and 5, what are: a) the mean absolute deviation? b) the mean squared error? Problem 2: If the forecast errors for five consecutive periods are 8, -5, -7, 9, and 4, what are: a) the mean absolute deviation? b) the mean squared error? Problem 3: Using the data below: Period Sales 1 643 2 582 3 601 4 613 5 595 6 625 a) Find the forecast for period 6 using the nave method. b) Find the forecast for period 7 based on a two-period moving average. c) Find the forecast for period 7 based on a four-period moving average. d) Find the forecast for period 7 based on a four-period weighted moving average using the following weights: 1 period prior 0.4 2 periods prior 0.3 3 periods prior 0.2 4 periods prior 0.1 e) Find the forecast for period 7 based on exponential smoothing with alpha = 0.7 and assuming that the forecast for period 4 was 600.