命令(面板数据已设定)
xtserial y x
是检验gls前的序列相关?还是检验gls后什么的的序列相关?
检验的目的是什么?
Wooldridge test for serial correlation in panel-data models
xtserial depvar [varlist] [if exp] [in range] [, output]
You must tsset your data before using xtserial; see help tsset.
Description
xtserial implements a test for serial correlation in the idiosyncratic
errors of a linear panel-data model discussed by Wooldridge (2002).
Drukker (2003) presents simulation evidence that this test has good
size and power properties in reasonable sample sizes.
Under the null of no serial the residuals from the regression of the
first-differenced variables should have an autocorrelation of -.5.
This implies that the coefficient on the lagged residuals in a
regression of the lagged residuals on the current residuals should be
-.5. xtserial performs a Wald test of this hypothesis. See Drukker
(2003) and Wooldridge (2002) for further details.
一个例题的执行结果:
. xtserial cp ip,out
Linear regression Number of obs = 224
F( 1, 15) = 1368.43
Prob > F = 0.0000
R-squared = 0.8634
Number of clusters (id) = 16 Root MSE = 66.027
------------------------------------------------------------------------------
| Robust
D.cp | Coef. Std. Err. t P>|t| [95% Conf. Interval]
------------+----------------------------------------------------------------
ip |
D1. | .7996297 .0216161 36.99 0.000 .7535561 .8457032
------------------------------------------------------------------------------
Wooldridge test for autocorrelation in panel data
H0: no first-order autocorrelation
F( 1, 15) = 64.220
怎样解释输出结果?
[此贴子已经被作者于2007-1-3 6:15:09编辑过]