What is Top2 coverage?

Top2 coverage checks whether the actual Pool A and Pool B patterns land in the two listed candidate scenarios.

Plain meaning

Allotment prediction lists more likely Pool A/B patterns and marks the most likely one. Top2 coverage means the actual result was among the first two candidates. The main metric is still whether the top choice was right; Top2 only shows whether the main possibilities were included.

Why it matters

Allotment patterns can shift near thresholds. High Top2 coverage means the candidate set is useful, not that every tier's lot count is accurate.

How to read it

Read it with top-1 scenario hit rate, time-weighted relative error and P90. Coverage is not return prediction accuracy.

How it appears here

Allotment backtests use Top2 coverage to check whether the main allotment pattern was in the candidate set.

Common mistakes

Treating Top2 coverage as return prediction accuracy.
Assuming high Top2 means the top choice was correct.
Overreading the metric when sample size is small.