What does the mean absolute percentage deviation function reveal about forecast values?

The mean absolute percentage deviation (MAPD) function is used to measure the accuracy of forecast values by analyzing how far those forecasts deviate from actual observed values relative to the actual values themselves. It provides insight into the magnitude of errors between forecasts and actual outcomes, allowing for a clear understanding of overall forecasting performance.

By expressing these deviations as a percentage, MAPD facilitates easy comparisons across different datasets or time periods, regardless of the scale of the actual values. This interpretation helps identify trends in forecasting accuracy and informs decision-making around improving future forecasts. Therefore, this function directly addresses how forecast values deviate from the actual values, which aligns with the correct answer.