除了估计方法的不同之外,似乎确实主要是一个问题
词汇和语法的
# install.packages(c("wooldridge", "plm", "stargazer", "lme4"), dependencies = TRUE)
library(wooldridge)
library(plm)
#> Le chargement a nécessité le package : Formula
library(lme4)
#> Le chargement a nécessité le package : Matrix
data(wagepan)
您的第一个示例是一个忽略组的简单线性模型nr
.
你不能用 lme4 做到这一点,因为没有“随机效应”(在lme4
sense).
这就是 Gelman & Hill 所说的完整的池化方法。
Pooled.ols <- plm(lwage ~ educ + black + hisp + exper+I(exper^2)+ married +
union + factor(year), data = wagepan,
index=c("nr","year"), model="pooling")
Pooled.ols.lm <- lm(lwage ~ educ + black + hisp + exper+I(exper^2)+ married + union +
factor(year), data = wagepan)
你的第二个例子似乎相当于随机截距混合模型nr
作为随机效应(但所有预测变量的斜率都是固定的)。
这就是 Gelman & Hill 所说的部分池化方法。
random.effects <- plm(lwage ~ educ + black + hisp + exper + I(exper^2) + married +
union + factor(year), data = wagepan,
index = c("nr","year") , model = "random")
random.effects.lme4 <- lmer(lwage ~ educ + black + hisp + exper + I(exper^2) + married +
union + factor(year) + (1|nr), data = wagepan)
你的第三个例子似乎对应于一个案例nr
是一个固定效应,你
计算出不同的nr
每组的截距。
再说一遍:你不能这样做lme4
因为不存在“随机效应”(在lme4
sense).
这就是 Gelman & Hill 所说的“无池化”方法。
fixed.effects <- plm(lwage ~ I(exper^2) + married + union + factor(year),
data = wagepan, index = c("nr","year"), model="within")
wagepan$nr <- factor(wagepan$nr)
fixed.effects.lm <- lm(lwage ~ I(exper^2) + married + union + factor(year) + nr,
data = wagepan)
比较结果:
stargazer::stargazer(Pooled.ols, Pooled.ols.lm,
random.effects, random.effects.lme4 ,
fixed.effects, fixed.effects.lm,
type="text",
column.labels=c("OLS (pooled)", "lm no pool.",
"Random Effects", "lme4 partial pool.",
"Fixed Effects", "lm compl. pool."),
dep.var.labels = c("log(wage)"),
keep.stat=c("n"),
keep=c("edu","bla","his","exp","marr","union"),
align = TRUE, digits = 4)
#>
#> =====================================================================================================
#> Dependent variable:
#> ----------------------------------------------------------------------------------------
#> log(wage)
#> panel OLS panel linear panel OLS
#> linear linear mixed-effects linear
#> OLS (pooled) lm no pool. Random Effects lme4 partial pool. Fixed Effects lm compl. pool.
#> (1) (2) (3) (4) (5) (6)
#> -----------------------------------------------------------------------------------------------------
#> educ 0.0913*** 0.0913*** 0.0919*** 0.0919***
#> (0.0052) (0.0052) (0.0107) (0.0108)
#>
#> black -0.1392*** -0.1392*** -0.1394*** -0.1394***
#> (0.0236) (0.0236) (0.0477) (0.0485)
#>
#> hisp 0.0160 0.0160 0.0217 0.0218
#> (0.0208) (0.0208) (0.0426) (0.0433)
#>
#> exper 0.0672*** 0.0672*** 0.1058*** 0.1060***
#> (0.0137) (0.0137) (0.0154) (0.0155)
#>
#> I(exper2) -0.0024*** -0.0024*** -0.0047*** -0.0047*** -0.0052*** -0.0052***
#> (0.0008) (0.0008) (0.0007) (0.0007) (0.0007) (0.0007)
#>
#> married 0.1083*** 0.1083*** 0.0640*** 0.0635*** 0.0467** 0.0467**
#> (0.0157) (0.0157) (0.0168) (0.0168) (0.0183) (0.0183)
#>
#> union 0.1825*** 0.1825*** 0.1061*** 0.1053*** 0.0800*** 0.0800***
#> (0.0172) (0.0172) (0.0179) (0.0179) (0.0193) (0.0193)
#>
#> -----------------------------------------------------------------------------------------------------
#> Observations 4,360 4,360 4,360 4,360 4,360 4,360
#> =====================================================================================================
#> Note: *p<0.1; **p<0.05; ***p<0.01
Gelman A, Hill J (2007) 使用回归和多级/分层模型进行数据分析。剑桥大学出版社
(一本非常非常好的书!)
创建于 2018-03-08 由代表包 http://reprex.tidyverse.org(v0.2.0)。