Multi-Treatment Designs

GeoSC supports several treated geographies, but interpretation and computation change.

The top-level effect is joint across the treated set; it is not a separate ATT for each geography. Placebo assignments must contain the same number of control units as the treated set, giving $\binom{N_0}{N_1}$ possible assignments. SparseSC work can grow rapidly, so sparse_sc_max_n_pl may trigger sampling.

Power injects the same absolute effect path into every treated unit, based on the pooled treated pre-period mean. This is not unit-specific proportional lift. When treated units have very different outcome levels, supplement the standard run with a carefully labelled sensitivity analysis or avoid describing the injected effect_size as each unit’s own percentage lift.

Confirm that all treated units share a defensible launch and measurement window. Staggered adoption requires a distinct design argument; do not coerce it into a single-date configuration without defining the resulting estimand.