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st: xi and i. command
From
Wolney Conde <[email protected]>
To
statalist <[email protected]>
Subject
st: xi and i. command
Date
Tue, 23 Nov 2010 11:38:54 -0200
Dear listers,
recently I did a mistake using <xi> to create indicator variable and
found an unknown [for me at least] performance in Stata. I type
<i.variable> without prefix <xi:> and have same results as when I type
<xi:command var1 i.var2>. The outputs are seen below. Is that an
undocumented feature of Stata? I couldn't find out anything about.
Thanks in advanced for some advice,
Wolney
. svy:poisson spi i.quintil agey if survey==1,ir
(running poisson on estimation sample)
Survey: Poisson regression
Number of strata = 22 Number of obs = 31449
Number of PSUs = 97 Population size = 11633525
Design df = 75
F( 5, 71) = 56.31
Prob > F = 0.0000
------------------------------------------------------------------------------
| Linearized
spi | IRR Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
quintil |
2 | 1.326016 .2605931 1.44 0.155 .8964478 1.96143
3 | 2.483046 .4851331 4.66 0.000 1.682486 3.664527
4 | 2.720255 .5983007 4.55 0.000 1.75519 4.215947
5 | 6.544557 1.153084 10.66 0.000 4.607317 9.296348
|
agey | .9984916 .0156243 -0.10 0.923 .9678466 1.030107
------------------------------------------------------------------------------
. xi:svy:poisson spi i.quintil agey if survey==1,ir
i.quintil _Iquintil_1-5 (naturally coded; _Iquintil_1 omitted)
(running poisson on estimation sample)
Survey: Poisson regression
Number of strata = 22 Number of obs = 31449
Number of PSUs = 97 Population size = 11633525
Design df = 75
F( 5, 71) = 56.31
Prob > F = 0.0000
------------------------------------------------------------------------------
| Linearized
spi | IRR Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
_Iquintil_2 | 1.326016 .2605931 1.44 0.155 .8964478 1.96143
_Iquintil_3 | 2.483046 .4851331 4.66 0.000 1.682486 3.664527
_Iquintil_4 | 2.720255 .5983007 4.55 0.000 1.75519 4.215947
_Iquintil_5 | 6.544557 1.153084 10.66 0.000 4.607317 9.296348
agey | .9984916 .0156243 -0.10 0.923 .9678466 1.030107
------------------------------------------------------------------------------
--
Wolney Conde
Department of Nutrition
School of Public Health
University of Sao Paulo
Av. Dr. Arnaldo 715
01246-904 Sao Paulo, Brazil
phone: +55-11-30617705 extension 7873
fax: +55-11-30617705
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