I. Your numbers
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% of actual
II. Scorecard
Show the rows
III. What it says
How it’s scored
- Bias
- The total of forecast minus actual, divided by the total of the actuals. Negative means your forecasts ran low.
- Average miss
- The total of the misses, ignoring direction, divided by the total of the actuals (often called WAPE). Big periods count for more than small ones, so a miss on a tiny month can’t dominate.
- On target
- The share of forecasts within the tolerance you set. Rows with an actual of zero are left out of the percentage measures.
- Order
- Rows are read in the order you paste them, so put the oldest first. “The last 12” means the bottom 12 rows.
- Brier score
- The average of (probability − outcome)², where the outcome is 1 if it happened and 0 if not. Zero is perfect, and always saying 50% scores 0.25.
- Skill
- How much better your Brier score is than always forecasting the overall rate in your own data. Above zero means your forecasts add something.
- Calibration
- Forecasts grouped in 10-point bands. In a well-calibrated set, things you call 70% happen about 70% of the time.
Contact
Want this run on your team’s forecasts every month? Write to hello@halberesford.com.