The effects of immigration are often localized and context-specific.
移民的影响往往是局部的,并且与具体背景相关。
当随机化不可行时,匹配方法可以是一个强大的工具。
不要害怕放弃好的东西去追求伟大的东西。
History has neither the desire nor the capacity to make men better or worse; it merely records what they have been and what they have done.