## Problem 063 — rank:221

**Title:** General variant-effect prediction

**Added binding assumptions (LaTeX):**

```latex
Interpret $\Delta f$ and $\Delta Y$ as contrasts of population mean responses under matched intervention protocols, and the predicted joint law as uncertainty about those contrasts. A distribution of individual treatment effects instead needs an explicit coupling of counterfactual outcomes, which parallel intervention arms do not identify. Coverage is evaluated under the stated sampling and transfer distribution.
```

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