The WTO trade effect

► This paper re-examines the GATT/WTO membership effect on bilateral trade flows, using nonparametric methods. ► The nonparametric methods used include pair-matching, permutation tests, and a Rosenbaum (2002) sensitivity analysis. ► This estimation framework is robust to misspecification bias, allows general forms of heterogeneous membership effects, and addresses potential selection bias. ► Our results suggest large GATT/WTO trade-promoting effects. ► The finding is robust to various matching criteria/methodologies, alternative GATT/WTO indicators, zero trade flows, and multilateral trade resistance.