## Problem 218 — rank:13

**Title:** Forecasting pathogen emergence

**Added binding assumptions (LaTeX):**

```latex
Distinguish a newly recorded event from a latent true event; label sensitivity applies to the latter through an explicit detection layer. Fix the target and do not switch between them during calibration evaluation. A constant target base rate can be perfectly calibrated, so useful forecasting additionally needs a prespecified proper-score improvement or discrimination margin. Rare-event clustering and archival selection determine the effective number of independent validation events.
```

**Direct edits:** 0. **Fresh external checks:** None; supplied sources retained as provenance.