Are The Poverty Effects of Trade Policies Invisible?
用随机模拟方法检验贸易自由化的贫困效应是否因市场波动而难以识别，发现全球主粮贸易完全自由化在短期内仅在15个国家中的4个有显著贫困影响。
Beginning with the WTO's Doha Development Agenda and establishment of the Millennium Development Goal of reducing poverty by 50 percent by 2015, poverty impacts of trade reforms have become central to the global development agenda. This has been particularly true of agricultural trade reforms due to the importance of grains in the diets of the poor, presence of relatively higher protection in agriculture, as well as heavy concentration of global poverty in rural areas where agriculture is the main source of income. Yet some in this debate have argued that, given the extreme volatility in agricultural commodity markets, the additional price and therefore poverty impacts due to trade liberalization might well be indiscernible. This paper formally tests the "invisibility hypothesis" using the method of stochastic simulation in a tradepoverty modeling framework. The hypothesis test is based on the comparison of two samples of price and poverty distributions. The first originates solely from the inherent variability in global staple grains markets, while the second combines the effects of inherent market variability with those of trade reform in these same markets. Results, at the national and stratum level indicate that the short-run poverty impacts of full trade liberalization in staple grains trade worldwide, are distinguishable in only four of the fifteen countries, suggesting that impacts of more modest agricultural trade reforms are indeed likely to be invisible in short run. Countries that show statistically significant short run impacts are the ones characterized by high staple grains tariffs and/or a moderate degree of grain markets variability. Within each country, results are heterogeneous. In two thirds of the sample countries, agriculturally self-employed poor experience statistically significant poverty impacts from trade liberalization. However, this figure is under a third for all the other strata. Agricultural trade reform,