For individual countries, variable trade barriers can be used to reduce the volatility of domestic relative to world prices. If this is done by countries accounting for a large share of the market, its effect is offset by increases in world price volatility. This study shows the nature of the...

The gravity model is now widely used for policy analysis and hypothesis testing, but different estimators give sharply different parameter estimates and popular estimators are likely biased because dependent variables are limited-dependent, error variances are nonconstant and missing data...