> At 02:53 PM 4/9/2007, S J wrote:
> >I estimate a model of the form
> >
> >xi: logit y x1 i.x2
> >
> >Then I attempt to do the below:
> >prvalue, x(x2=0) rest(mean)
> >prvalue, x(x2=1) rest(mean)
> >
> >But I get an error message:
> >x1 not rhs variable
> >invalid syntax
> >r(198);
> >
> >Any ideas? Is it that I can't use the xi route for
> >specifying categorical rhs's and then use prvalue?
--- Richard Williams <[email protected]> wrote:
> x2 isn't actually a variable in the equation. Dummies created from
> x2 are. So, I think you need to create the dummies
> yourself. Although, if x2 is already a dummy var, you don't need xi
> in the first place.
You can use -prvalue- directly after -xi- only you have to know how the
new variables -xi- creates are named. See, example below:
*-------------- begin example -----------
sysuse auto, clear
recode rep78 1/2=3
xi: logit foreign i.rep78 price mpg
/*probability for rep78==1-3*/
prvalue ,x(_Irep78_4=0 _Irep78_5=0) rest(mean)
/*probability for rep78==4*/
prvalue ,x(_Irep78_4=1 _Irep78_5=0) rest(mean)
/*probability for rep78==5*/
prvalue ,x(_Irep78_4=0 _Irep78_5=1) rest(mean)
*--------------- end example -----------
(For more on how to use examples I sent to the Statalist, see:
http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )
Hope this helps,
Maarten
-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands
visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
-----------------------------------------
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