Shipping the good agricultural products out: the differentiated impact of per-unit duties on developing countries
研究了从量税（按进口产品单位计价的关税）如何影响全球农产品贸易模式，发现其导致出口单价上升，且对发展中国家的贸易限制效应更强。
Abstract We investigate the impact of per-unit duties (i.e. tariffs expressed in US dollars per unit of imported product) on world agricultural trade patterns. Using detailed data on trade and tariffs, we show first that they induce higher export unit values, confirming that the Alchian–Allen conjecture can be extended to per-unit duties. Second, we show that this effect is higher for developed countries, which can be explained by their specialization on high-priced products. Third, we find that the restrictive effect of per-unit duties on trade is higher for developing countries.