Trade liberalisation effects on agricultural goods at different processing stages
研究使用两阶段引力模型分析42国间活牛和牛肉的双边贸易，发现关税削减等自由化措施会同时通过扩展边际和集约边际调整牛肉出口，且对发展中国家的扩展边际影响在完全自由化下是部分自由化的六倍。
A two-stage gravity-based model is used to explain cattle and beef bilateral trade flows between 42 countries. The model parameters are estimated using a double-hurdle model with a multivariate sample selection procedure. The parameter estimates are used to simulate probabilities of new trade flows and the increase in existing trade flows following reductions in import tariffs, export subsidies and domestic support. The results show that adjustments in beef exports occur at both the extensive and intensive margins. Full liberalisation would entail adjustments in the extensive margins for developing economies that are about six-fold the adjustments under partial liberalisation.