What Constrains Africa's Exports?
研究发现内陆运输延误对非洲出口影响最大，减少一天内陆运输时间可使出口增加7%，相当于降低2个百分点的进口国关税。
Africa's share of global exports has dropped by 50 percent over the last three decades. To stem this decline, aid for trade to the region has increased rapidly in recent years. Assistance can target improvements in three important components of trade facilitation: transit times, documentation, and ports and customs. Of these, transit delays have the most economically and statistically significant effect on exports. Specifically, a one day reduction in inland travel times leads to a 7 percent increase in exports, after controlling for the standard determinants of trade and potential endogeneity. Put another way, a one day reduction in inland travel times translates into a 2 percentage point decrease in all importing-country tariffs. By contrast, longer delays in the other areas have a far smaller impact on trade. Large transit delays are relatively more harmful because they are associated with high (within-country) variation, making delivery targets difficult to meet. Finally, the results imply that transit times are primarily about institutional features—such as border delays, road quality, fleet class and competition and security—and not geography.