Failed Donor Design

Consider a hypothetical treated geography with five candidate donors. Two have incomplete metrics and cannot receive recommendations. Of the remaining three, one receives 70% of the design-stage recommendation weight. The pool-level quality_assessment is INSUFFICIENT.

This is not a prompt to fit SparseSC and hope regularisation fixes the design. The donor screen says the counterfactual may depend on weak or concentrated comparators. Review time overlap, outcome definitions, treatment leakage, regional shocks, and geography aggregation. Exclude a donor only for a pre-specified eligibility reason, not because its removal improves the eventual effect estimate.

If eligibility changes, rerun donor screening, power, and inference on the same revised geography universe. If no defensible pool remains, reject the design and state which condition failed. See Design Rejection.