当随机化不可行时，匹配方法可以是一个强大的工具。
"Matching methods can be a powerful tool when randomization is not possible."
The whole conviction of my life now rests upon the belief that loneliness, far from being a rare and curious phenomenon, peculiar to myself and to a few other solitary men, is the central and inevitable fact of human existence.
The only real journey is the one within.
Every artist was first an amateur.