help xtreg dialog: xtreg
also see: xtreg postestimation
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Title
[XT] xtreg -- Fixed-, between-, and random-effects, and population-averaged linear models
Syntax
GLS random-effects (RE) model
xtreg depvar [indepvars] if [, re RE_options]
Between-effects (BE) model
xtreg depvar [indepvars] if , be [BE_options]
Fixed-effects (FE) model
xtreg depvar [indepvars] if , fe [FE_options]
ML random-effects (MLE) model
xtreg depvar [indepvars] if [weight] , mle [MLE_options]
Population-averaged (PA) model
xtreg depvar [indepvars] if [weight] , pa [PA_options]
RE_options description
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Model
i(varname_i) use varname_i as the panel ID variable
re use random-effects estimator; the default
sa use Swamy-Arora estimator of the variance components
SE/Robust
vce(vcetype) vcetype may be robust, bootstrap or jackknife
robust synonym for vce(robust)
cluster(varname) adjust standard errors for intragroup correlation
nonest do not check that panels are nested within clusters
Reporting
level(#) set confidence level; default is level(95)
theta report theta
BE_options description
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Model
i(varname_i) use varname_i as the panel ID variable
be use between-effects estimator
wls use weighted least squares
SE
vce(vcetype) vcetype may be bootstrap or jackknife
Reporting
level(#) set confidence level; default is level(95)
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FE_options description
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Model i(varname_i) use varname_i as the panel ID variable
fe use fixed-effects estimator
SE/Robust
vce(vcetype) vcetype may be robust, bootstrap or jackknife
robust synonym for vce(robust)
cluster(varname) adjust standard errors for intragroup correlation
nonest do not check that panels are nested within clusters dfadj adjust the cluster-robust VCE for the within transform; seldom used
Reporting
level(#) set confidence level; default is level(95)
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Description
xtreg fits cross-sectional time-series regression models. In particular, xtreg with the be option fits
random-effects models using the between regression estimator; with the fe option, it fits fixed-effects models
(using the within regression estimator); and with the re option, it fits random-effects models using the GLS
estimator (producing a matrix-weighted average of the between and within results). See xtdata for a faster way
to fit fixed- and random-effects models.
Options for BE model
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----+ Model +----------------------------------------------------------------------------------------------------
i(varname_i); see estimation options.
be requests the between regression estimator.
wls specifies that, in the case of unbalanced data, weighted least squares be used rather than the default OLS.
Both methods produce consistent estimates.
+----+
----+ SE +-------------------------------------------------------------------------------------------------------
nonest removes the check that the panels are nested within clusters. The cluster-robust VCE generally assumes
that the panels are nested within the clusters, or that there are many observations per panel.
dfadj adjusts the cluster-robust VCE for the within transform. dfadj will produce a conservative VCE when panels are not nested within clusters, even when there are only a few observations per panel.