LSC893045160 发表于 2013-8-11 22:11
面板数据也可以这样做吗??那用predict 可以得到估计值吗??两者什么区别??
help xtreg postestimation predict dialogs: re/be/fe/mle pa
dialog: xttest0
also see: xtreg
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Title
[XT] xtreg postestimation -- Postestimation tools for xtreg
Description
The following postestimation commands are of special interest after
xtreg:
command description
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xttest0 Breusch and Pagan LM test for random effects
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The following standard postestimation commands are also available:
command description
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(1) estat AIC, BIC, VCE, and estimation sample summary
estimates cataloging estimation results
hausman Hausman's specification test
lincom point estimates, standard errors, testing, and
inference for linear combinations of coefficients
lrtest likelihood-ratio test
margins marginal means, predictive margins, marginal effects,
and average marginal effects
nlcom point estimates, standard errors, testing, and
inference for nonlinear combinations of coefficients
predict predictions, residuals, influence statistics, and other
diagnostic measures
predictnl point estimates, standard errors, testing, and
inference for generalized predictions
test Wald tests of simple and composite linear hypotheses
testnl Wald tests of nonlinear hypotheses
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(1) estat ic is not appropriate with xtreg, be, xtreg, pa, or xtreg, re.
Special-interest postestimation commands
xttest0, for use after xtreg, re, presents the Breusch and Pagan
Lagrange multiplier test for random effects, a test that Var(v_i)=0.
Syntax for predict
For all but the population-averaged model
predict [type] newvar [if] [in] [, statistic nooffset]
Population-averaged model
predict [type] newvar [if] [in] [, PA_statistic nooffset]
statistic description
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Main
xb xb, fitted values; the default
stdp calculate standard error of the fitted values
ue u_i + e_it, the combined residual
* xbu xb + u_i, prediction including effect
* u u_i, the fixed- or random-error component
* e e_it, the overall error component
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Unstarred statistics are available both in and out of sample; type
predict ... if e(sample) ... if wanted only for the estimation sample.
Starred statistics are calculated only for the estimation sample, even
when if e(sample) is not specified.
PA_statistic description
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Main
mu probability of depvar; considers the offset()
rate probability of depvar
xb calculate linear prediction
stdp calculate standard error of the linear prediction
score first derivative of the log likelihood with respect to xb
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These statistics are available both in and out of sample; type predict
... if e(sample) ... if wanted only for the estimation sample.
Menu
Statistics > Postestimation > Predictions, residuals, etc.
Options for predict
+------+
----+ Main +------------------------------------------------------------
xb calculates the linear prediction, that is, a + bx_it. This is the
default for all except the population-averaged model.
stdp calculates the standard error of the linear prediction. For the
fixed-effects model, this excludes the variance due to uncertainty
about the estimate of u_i.
mu and rate both calculate the predicted probability of depvar. mu
takes into account the offset(), and rate ignores those adjustments.
mu and rate are equivalent if you did not specify offset(). mu is
the default for the population-averaged model.
ue calculates the prediction of u_it + e_it.
xbu calculates the prediction of a + bx_it + u_i, the prediction
including the fixed or random component.
u calculates the prediction of u_i, the estimated fixed or random
effect.
e calculates the prediction of e_it.
score calculates the equation-level score.
nooffset is relevant only if you specified offset(varname) for xtreg.
It modifies the calculations made by predict so that they ignore the
offset variable; the linear prediction is treated as xb rather than
xb + offset.
Syntax for xttest0
xttest0
Menu
Statistics > Longitudinal/panel data > Linear models > Lagrange
multiplier test for random effects
Examples
Setup
. webuse nlswork
. xtset idcode
Fit random-effects model
. xtreg ln_w grade age c.age#c.age ttl_exp c.ttl_exp#c.ttl_exp
tenure c.tenure#c.tenure 2.race not_smsa south, re
Store random-effects results for later use
. estimates store random_effects
Breusch and Pagan Lagrangian multiplier test for random effects
. xttest0
Fit fixed-effects model
. xtreg ln_w grade age c.age#c.age ttl_exp c.ttl_exp#c.ttl_exp
tenure c.tenure#c.tenure 2.race not_smsa south, fe
Hausman specification test
. hausman . random_effects
Also see
Manual: [XT] xtreg postestimation
Help: [XT] xtreg