International trade policies are often compared across countries and over time for a variety of purposes. Analysts use such measures as arithmetic or trade-weighted average tariffs, Non-Tariff Barrier (NTB) coverage ratios and measures of tariff dispersion. All such measures are without...

We show that the effects of tariff changes on welfare and import volume can be fully characterised by their effects on the generalised mean and variance of the tariff distribution. Using these tools, we derive new results for welfare- and market-access-improving tariff changes, which imply two...

Historical evidence suggests that Mafias originally formed to provide enforcement of legitimate property rights when state enforcement was weak. We provide a general equilibrium model of Mafias as enforcement coalitions which protect property from predators. Both the level of predation and the...

The gravity model has been widely used to infer substantial trade flow effects of institutions such as customs unions and exchange rate mechanisms. McCallum [1995] found that the US-Canada border led to trade between provinces that was a factor 22 (2,200%) times trade between states and...

Corruption and imperfect contract enforcement dramatically reduce trade. This paper estimates the reduction, using a structural model of import demand in which transactions costs impose a price markup on traded goods. We find that inadequate institutions constrain trade far more than tariffs do....

This paper provides striking confirmation of the restrictions of the structural gravity model of trade. Structural forces predicted by theory explain 95% of the variation of the fixed effects used to control for them in the recent gravity literature, fixed effects that in principle could reflect...

Are bigger markets safer? How should government policy respond to terrorist threats? Trade draws potential terrorists and economic predators into productive activity, but trade also draws terrorist attacks. Larger trade reduces the risk of terrorist attack when the wage elasticity is high,...

Much empirical work requires the aggregation of policies. This paper provides methods of policy aggregation that are consistent with two common objectives of empirical work. One is to preserve real income. The other is to preserve the real volume of activity in one or more parts of the economy....

Without the rule of law, traders who incur trading costs can be held up by counter-parties who are stronger in anarchic bargaining. The favourable terms which the latter extract can overcrowd that side of the market, dissipating the benefits. We establish plausible necessary and sufficient...