Final answer:
The Mean Absolute Deviation (MAD) is used to describe the degree of error, indicating how spread out values are from the average, while the forecast as a percent of actual is used to measure the accuracy of a forecast.
Step-by-step explanation:
To describe the degree of error in a set of data, the Mean Absolute Deviation (MAD) is commonly used. MAD is a statistic that measures the average of the absolute differences between each value in a set of numbers and the overall average of the set. It reflects how 'spread out' the values are, and a smaller MAD indicates that the numbers are closer to the average, hence showing a higher precision. In contrast, the forecast as a percent of actual is a measure used to compare the forecast numbers directly with the actual numbers to evaluate the accuracy of the forecast. It indicates the extent to which the forecast deviates from the actual values. A lower percent indicates a more accurate forecast. The use of regression could also relate to error measurement when assessing the goodness of fit of a regression model but is not the direct measure of error itself.