黃河泉 发表于 2017-3-23 15:46
不知道什么原因,我看不到 Wooldridge 之回答内容,当然,他是这领域的大牛,他讲的大概是不会错的!
啊!我有时候也打不开,好像是浏览器的问题。他的回答如下:
22 May 2015, 16:43
I cover this in Section 19.6.2 in the second edition of "Econometric Analysis of Cross Section and Panel Data," MIT Press, 2010. You are on the right track, but here are the specifics.
1. Estimate a probit model for the selection indicator, I. Include all exogenous variables: Those in the equation for Y1, the instrument(s) for Y2, and the variable determining selection. To be convincing, you should argue that you have two sources of exogenous variation excluded from the equation for Y1. Call these Z2 and Z0.
Code:
probit I Xb Xc Z2 Z0
2. Obtain the inverse Mills ratios from step 1 -- say IMR.
(code omitted)
3. Estimate the structural equation by 2SLS:
Code:
ivregress 2sls Y1 Xb Xc IMR (Y2 = Z2)
Note that the IMR, depending only on exogenous variables, acts as its own IV.
The standard errors are incorrect if the coefficient on IMR is not zero (in the population). Bootstrapping the entire procedure is not very difficult.
I hope this helps. JW
我想请教的是他所说的Bootstrapping the entire procedure ,就是简单的在回归后面加上 vce(bootstrap)或类似的处理吗?