A new road connects a village in Bihar to a market, school, and clinic. Travel time falls immediately; wages, schooling, migration, land prices, and firm entry may change later and differently. A before-and-after photograph proves construction, not the entire development claim. A randomized or quasi-experimental study can estimate selected effects, but its result still depends on implementation and context. Policy judgment begins by separating the chain and assigning confidence to each link.

India’s scale and federal diversity make policy evidence both valuable and difficult to transfer. Reforms arrive with political narratives, administrative dashboards, research designs, and lived accounts that observe different layers. The temptation is to choose one authoritative-looking result. A better approach grades implementation, intended output, outcome, attribution, and distribution separately. It then asks whether the mechanism would travel to another place or period.

Trade-liberalization research illustrates regional exposure and uneven effects; rural-road evaluation illustrates infrastructure and causal design; the Economic Survey provides broad policy context; RBI data supply macro and state indicators for monitoring. Use research papers for methods and estimated effects, administrative records for delivery, and official statistics for background trends. A source can be rigorous for one claim and silent on another. Authority does not erase scope.