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st: RE: Xtpoisson and quadchk
From
"Jesper Lindhardsen" <[email protected]>
To
<[email protected]>
Subject
st: RE: Xtpoisson and quadchk
Date
Tue, 22 Mar 2011 08:45:33 +0100
Hi Garry,
My guess is that it has something to do with how you defined/created
your 'service' variable as it is indeed your offset if I understand your
model correctly (exposure(service) = offset(ln(service)) - see help
-xtpoisson-).
HTH,
Jesper
Jesper Lindhardsen
MD, PhD candidate
Department of Cardiovascular Research
Copenhagen University Hospital, Gentofte
Denmark
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Garry
Anderson
Sent: 22 March 2011 08:31
To: [email protected]
Subject: st: Xtpoisson and quadchk
Dear Statalisters,
The message after the -quadchk- command seems a little strange.
The message is
Refitting model intpoints() = 8
factor variables and time-series operators not allowed
in option offset()
error refitting model
r(101);
I do not think I am using a factor variable nor a time-series operator,
and I am not using the offset option.
Any ideas as to the meaning of this message would be appreciated.
. use http://www.stata-press.com/data/r11/ships,clear
. xtpoisson accident op_75_79 co_65_69 co_70_74 co_75_79,
exposure(service) irr normal
Fitting comparison Poisson model:
Iteration 0: log likelihood = -147.37993
Iteration 1: log likelihood = -80.372714
Iteration 2: log likelihood = -80.116093
Iteration 3: log likelihood = -80.115916
Iteration 4: log likelihood = -80.115916
Fitting full model:
tau = 0.0 log likelihood = -80.115916
tau = 0.1 log likelihood = -76.060792
tau = 0.2 log likelihood = -77.535639
Iteration 0: log likelihood = -76.360754
Iteration 1: log likelihood = -75.585665
Iteration 2: log likelihood = -74.788481
Iteration 3: log likelihood = -74.780993
Iteration 4: log likelihood = -74.780982
Iteration 5: log likelihood = -74.780982
Random-effects Poisson regression Number of obs =
34
Group variable: ship Number of groups =
5
Random effects u_i ~ Gaussian Obs per group: min =
6
avg =
6.8
max =
7
Wald chi2(4) =
50.95
Log likelihood = -74.780982 Prob > chi2 =
0.0000
------------------------------------------------------------------------
------
accident | IRR Std. Err. z P>|z| [95% Conf.
Interval]
-------------+----------------------------------------------------------
------
op_75_79 | 1.466677 .1734403 3.24 0.001 1.163259
1.849236
co_65_69 | 2.032604 .3040933 4.74 0.000 1.516025
2.725205
co_70_74 | 2.357045 .3998397 5.05 0.000 1.690338
3.286717
co_75_79 | 1.646935 .3820235 2.15 0.031 1.045278
2.594905
service | (exposure)
-------------+----------------------------------------------------------
------
/lnsig2u | -2.351868 .8586262 -2.74 0.006 -4.034745
-.6689918
-------------+----------------------------------------------------------
------
sigma_u | .3085306 .1324562 .1330045
.7156988
------------------------------------------------------------------------
------
Likelihood-ratio test of sigma_u=0: chibar2(01) = 10.67 Pr>=chibar2 =
0.001
. quadchk
Refitting model intpoints() = 8
factor variables and time-series operators not allowed
in option offset()
error refitting model
r(101);
.
Best wishes, Garry
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