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Antwort: Re: RE: Antwort: st: 'mills' output is missing for heckman regression
From
Richard Ochmann <[email protected]>
To
[email protected]
Subject
Antwort: Re: RE: Antwort: st: 'mills' output is missing for heckman regression
Date
Fri, 14 May 2010 13:52:32 +0200
well, it is all about your first observation as I see it if you call
-display- here. If the first observation is excluded from your regression
(which only you know), the Mills ratio will be missing for it. The
selection probability you however predict out of sample so that it is
non-missing for your first observation.
best, rich
[email protected] schrieb am 14.05.2010 13:04:31:
> Hi,
>
> yes that is the problem i am facing with now.
>
> I don't know why mills200412 is missing. I use the same regression and
> postestimation for another two year data. it works fine. but only this
> one is missing.
>
> do you know why??
>
>
> thanks
>
> best
>
> Jing
>
> On Fri, May 14, 2010 at 6:10 PM, Richard Ochmann <[email protected]>
wrote:
> > Nick is right, I was too sloppy here.
> >
> > The output suggests that mills200412[1] is missing, which is why
Dpr200412
> > [1] turns out to be missing as well, while selpr200412[1] is
.30568352.
> > I cannot see the reason for this alone from the code given.
> >
> > best, rich
> >
> >> . predict selpr200412, psel
> >> (32284 missing values generated)
> >>
> >> . gen Dpr200412=mills200412*(mills200412+selpr200412)
> >> (159277 missing values generated)
> >>
> >> . display Dpr200412
> >> .
> >>
> >> . display selpr200412
> >> .30568352
> >>
> >> . display mills200412
> >
> >
> > [email protected] schrieb am 14.05.2010 11:54:18:
> >
> >> Not so simple:
> >>
> >> 1. -di varname- is perfectly legal and is equivalent to -di
varname[1]-.
> >>
> >>
> >> 2. Clearly that is not equivalent to e.g. -list varname-.
> >>
> >> 3. But if a constant were being held in a variable, -di varname- is
> >> sufficient to see what it is.
> >>
> >> 4. That is not especially good in terms of either style or
efficiency,
> >> but that is another story.
> >>
> >> Nick
> >> [email protected]
> >>
> >> Richard Ochmann
> >> Sent: 14 May 2010 09:21
> >> To: [email protected]
> >> Subject: Antwort: st: 'mills' output is missing for heckman
regression
> >>
> >> all I can see here is that at your 'problem 2' you try to -display-
> >> variables which won't work.
> >>
> >> *
> >> * For searches and help try:
> >> * http://www.stata.com/help.cgi?search
> >> * http://www.stata.com/support/statalist/faq
> >> * http://www.ats.ucla.edu/stat/stata/
> >
> > *
> > * For searches and help try:
> > * http://www.stata.com/help.cgi?search
> > * http://www.stata.com/support/statalist/faq
> > * http://www.ats.ucla.edu/stat/stata/
> >
>
>
>
> --
> Best
>
> 刘京 Jing LIU
>
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
*
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