st: Re: defiing the reference category in multinominal logistic regression

["Martin Weiss" <martin.weiss1@gmx.de>]

<>

Dan,

you do not even apply -xi- to your dependent in the lines

***
-char flushot[omit] 2
-xi: svy: mlogit flushot i.adjsmoker i.ageg i.rostsex i.myrace i.my_income 
i.my_ed i.my_dwell i.placepar , rr
***

You say "flushot", not "i.flushot"! In fact, the first line here has no 
effect whatsoever on the second line.
The base category for -mlogit- is specified as -baseoutcome()-. -xi- has no 
bearing on it.

The change in the base category observed in your example is entirely due to 
the default being the most frequent value of your dependent, and the change 
you enforce in the second example via "b(2)".


HTH
Martin
_______________________
----- Original Message ----- 
From: "Dan Waldo" <dan_waldo@yahoo.com>
To: <statalist@hsphsun2.harvard.edu>
Sent: Saturday, March 28, 2009 4:13 PM
Subject: st: defiing the reference category in multinominal logistic 
regression


> Hello, all ...
>
> I am running Stata10/SE, and am doing a series of multinomial logistic 
> regressions.
>
> It's clear that Stata uses information from the
> char ageg[omit] 3
> instruction (for example) when setting up the explanatory variables. But 
> such is not the case for the dependent variable.
>
> Again for example, the variable flushot is dichotemous with values 1,2 
> referring to yes,no.
>
> -char flushot[omit] 2
> -xi: svy: mlogit flushot i.adjsmoker i.ageg i.rostsex i.myrace i.my_income 
> i.my_ed i.my_dwell i.placepar , rr
>
> produces a regression in which (flushot==Yes is the base outcome)
>
> -xi: svy: mlogit flushot i.adjsmoker i.ageg i.rostsex i.myrace i.my_income 
> i.my_ed i.my_dwell i.placepar , rr b(2)
>
> produces a regression in which (flushot==No is the base outcome)
>
> Am I out of luck is hoping that Stata will use the default reference 
> category when the variable is used as a dependent variable?
>
> Dan Waldo
>
>
>
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