Mean absolute deviation (MAD), mean square error (MSE) and mean absolute percent error (MAPE) are all measures of Question 4Answer a. forecast accuracy, summarizing the degree to which actual values differed from predictions for previous periods, on average b. The tracking signal (TS) is a measure of the bias of the differences between the actual values and the predictions. c. are basic inputs and references in the decision process providing information on future demand. d. all of a and b above