Forecast Error Measures

Scoreboard has templates for many of the common measures used for error analysis.

The scoreboards can display the error values but you can also construct the error values in a favorite view as a Calculated Measure.

Creating a scoreboard from a Formula Template is possible through the right-click option Properties for a scoreboard record. Select Calculation Setup from the Select Property column.

M3 DMP will display the Calculation Parameters dialog box with the formula at the bottom of the display. You can copy the formula and make it into a calculated measure in a favorite view, for example, if the scoreboard is not used when opening the favorite view or using the favorite view data manager to copy the values across favorite views.

List of common forecast error measures

Measure Formula
Mean Forecast Error (MFE) MFE: Avg(3,[M1] - [M2])
Mean Absolute Deviation (MAD) MAD: Avg(3,Abs([M1] - [M2]))
Mean Absolute Percentage Error (MAPE) MAPE: Avg(3,Abs(([M1] - [M2]) / [M1]))

This is a common and useful indicator that gives relative information about the difference between two measures. Demand vs. Forecast or Forecast vs Sales, and so on.

Mean Squared Error (MSE) MSE: Avg(3,([M1] - [M2])^2)
Root Mean Squared Error (RMSE) RMSE: Sqr(Avg(3,([M1] - [M2])^2))
Tracking Signal (TS) TS: Sum(3,([M1] - [M2])) / Abs(([M1] - [M2]))

Tracking signal is used for accumulating errors over time to detect when the basic pattern has changed. Typically, the forecaster needs to be notified when the tracking signal falls outside certain limits so that you can apply a new forecast model or a manual correction.

Accuracy Signal (AS) AS: ([M1] - [M2]) / ([M1] + [M2])

Accuracy Signal gives an indicator to how close we are to a perfect forecast and if we are overshooting or undershooting.

  • AS = 0: Perfect
  • AS < 0: Undershooting AS = -0.333, means M2 = 2 * M1, and AS= -0.048 means M2 is 10% more than M2
  • AS > 0: Overshooting AS = 0.333, means M1 = 2*M2
Note: AS has the same scale for positive and negative values.
Theil's U-statistic (Theil's U) Theil's U: Sqr(Sum(3,(([M1][P + 1] - [M2][P + 1]) / [M2][P])^2)/Sum(3,(([M2][P + 1] - [M2][P]) / [M2][P])^2))

This provides a relative comparison and also squares the errors involved so that large errors are given more weight than small errors. Theil's U describes how good a fit two measures are.

  • U = 1: The naïve method is as good as the technique used, for example, taking a copy of the last year's sales or repeating the last demand is as good as a guess.
  • U < 1: The method used is better than a simple naive guess. The smaller Theil's U is, the better (U = 0 is a perfect prediction).
  • U > 1: The method used is worse than simple using a naïve method. The copy of last year's sales gives a better forecast.
Note:  These forecast methods are available for Scoreboards and for Competitive Forecasting.