MetricUpdated: 2026-07-09
What is Top2 coverage?
Top2 coverage checks whether the actual outcome lands in the model's two most likely scenarios.
Plain meaning
Allotment prediction can produce several possible Pool A/B scenarios. If the actual pattern is inside the two highest-probability scenarios, it counts as covered.
Why it matters
Allotment rules can shift discretely near thresholds. Top2 coverage shows whether the model captured the main plausible modes.
How to read it
Read it with P90 relative error, weighted relative error and sample size. High coverage does not mean every tier has low error.
How it appears here
Allotment backtests use Top2 coverage to evaluate scenario ranking under different demand regimes.
Common mistakes
- Treating Top2 coverage as return prediction accuracy.
- Ignoring tier-level error.
- Overreading the metric when sample size is small.