Notes: Gamma Pseudo Maximum Likelihood estimation of the gravity model in Eq. (2). The dependent variable is the value of bilateral trade (in level). The TBT-related explanatory variables are modeled as dummy variables. B14 and B15 consist, respectively, in authorization requirement and in registration requirement for importers for TBT reasons (including environmental protection); B21 are tolerance limits for residues of or contamination by certain substances. All specifications include a constant, importer, time, exporter-time, and country-pair fixed effects, tariff levels. “+” indicates a positive significant relationship, “-” indicates a negative significant relationship, “n.s.” stands for not significant.