当随机化不可行时，匹配方法可以是一个强大的工具。

最伟大的经济转型往往始于小而深思熟虑的步骤。

I'm not perfect, but I'm trying.

You’ve got to have models in your head. And you’ve got to array your experience—both vicarious and direct—on this latticework of models. You may have noticed students who just try to remember and pound back what is remembered. Well, they fail in school and in life. You’ve got to hang experience on a latticework of models in your mind.

语言既是桥梁也是障碍，它连接我们也分隔我们。