A sports economic impact study measures the contribution of a sporting event or facility to a host economy. A rigorous study goes beyond headline GDP to quantify employment, fiscal return, hotel demand, air route activation, infrastructure utilisation, and supply-chain effects. Conducting one requires event-level data (dates, location, attendance, expenditure), robust economic modelling (input-output tables or computable general equilibrium models) and transparent assumptions covering additionality, displacement, leakage, and counterfactuals. The most useful studies are OECD-compliant, assumption-transparent, and built for two audiences at once: the finance ministry that approves the spending and the public that needs to understand why it matters.