我正试图ivreg()
从 {AER} 包中解释 R 中命令的诊断。运行帮助页面中提供的示例代码:
## data
data("CigarettesSW", package = "AER")
CigarettesSW$rprice <- with(CigarettesSW, price/cpi)
CigarettesSW$rincome <- with(CigarettesSW, income/population/cpi)
CigarettesSW$tdiff <- with(CigarettesSW, (taxs - tax)/cpi)
## model
fm <- ivreg(log(packs) ~ log(rprice) + log(rincome) | log(rincome) + tdiff + I(tax/cpi), data = CigarettesSW, subset = year == "1995")
summary(fm, vcov = sandwich, df = Inf, diagnostics = TRUE)
您会得到以下输出:
Call:
ivreg(formula = log(packs) ~ log(rprice) + log(rincome) | log(rincome) +
tdiff + I(tax/cpi), data = CigarettesSW, subset = year ==
"1995")
Residuals:
Min 1Q Median 3Q Max
-0.6006931 -0.0862222 -0.0009999 0.1164699 0.3734227
Coefficients:
Estimate Std. Error z value Pr(>|z|)
(Intercept) 9.8950 0.9288 10.654 < 2e-16 ***
log(rprice) -1.2774 0.2417 -5.286 1.25e-07 ***
log(rincome) 0.2804 0.2458 1.141 0.254
Diagnostic tests:
df1 df2 statistic p-value
Weak instruments 2 44 228.738 <2e-16 ***
Wu-Hausman 1 44 3.823 0.0569 .
Sargan 1 NA 0.333 0.5641
我对诊断测试的解释很感兴趣。这是否意味着这些工具很弱或没有?考虑到它在 10% 的水平上显着,Wu-Hausman 是什么意思?Sargan 不重要意味着什么?