The threshold it used for “middle-classness” was a self-reported income of $4,286 a year in 2007 PPP dollars, consistent with the range of $4,000-17,000 a year used by the World Bank.
皮尤中心设定的“中产阶级”门槛以2007年购买力平价币值计算,为自报年收入4,286元,这与世界银行所用的4,000-17,000美元的年收入范围一致。