The third major challenge is using PPP estimates, measured in national currencies, to convert survey data into global poverty estimates that account for cost-of-living differences between countries. Given that the conversions that the World Bank currently uses are based on an international exercise that was conducted for 2005, they fail to account for recent factors that are significantly affecting the poor and vulnerable, such as much higher prices for staple foods.
第三个重大挑战是，将调查数据转换为全球贫困估计值（解释国家间生活成本差异）时用的是PPP估计（用国家货币计量）。世界银行目前使用的转换方法基于2005年制定的国际执行标准，无法解释对贫困和脆弱（比如主食价格大幅上涨）具有重大影响的最新因素。