The Changing Incidence of Geography
利用结构引力模型计算双边贸易成本的归宿，发现加拿大各省的卖方承担的成本平均是买方的五倍，且随时间下降，这推动了本地贸易偏好的减少和实际GDP的增长。
The incidence of bilateral trade costs is calculated here using neglected properties of the structural gravity model, disaggregated by commodity and region, and re-aggregated into forms useful for economic geography. For Canada's provinces, 1992–2003, sellers' incidence is on average some five times higher than buyers' incidence. Sellers' incidence falls over time due to specialization, despite constant gravity coefficients. This previously unrecognized globalizing force drives big reductions in “constructed home bias,” the disproportionate predicted share of local trade; and large but varying gains in real GDP.