夸克之一 发表于 2012-7-13 07:49 
The regional unobserved characteristics, such as economic development is partial out when province ...
The compulsory law is arguably exogenous because any law is still decision. However, we can buy that because otherwise we have nothing. However, the main variation in the paper is the different implementation period in different region this is definitely related to regional structure and output which is related to individual unobserbables such as their social relations, their virtues, etc. For example, in a region where people think education is totally useless, that will affect the implementation of the law, the attitude in taking the education (number of years) and the output. Regional dummies help however it's not clear how much it helps because it only captures something constant. Anyway, I am not saying this instrument is useless at all. It is questionable.