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RE: st: how to make xi dummies inherit labels


From   John Hendrickx <john_hendrickx@yahoo.com>
To   statalist@hsphsun2.harvard.edu
Subject   RE: st: how to make xi dummies inherit labels
Date   Thu, 3 Oct 2002 06:37:04 -0700 (PDT)

Hello once again,

I've forgoten my own command syntax, it should be:

desmat: logistic siweekT2 age10yy2, desrep(exp)

There's an example on this in the help file although I suppose you do
have to know where to find it.

As for the speed problems, I'm mystified. I just tried a dataset with
20375 cases and 238 variables and that was no problem (although I did
have to increase matsize and memory). You might want to try desmat as
a command, see if that sheds some light on the problem:

desmat age10yy2
logistic siweekT2 _x_*
desrep, exp
drop _x_*

Of course, if you already have an alternative solution then there's
no need to waste any more time, but I'm curious about this speed
problem with desmat. Pretty strange.

John Hendrickx

--- Roger Harbord <Roger.Harbord@bristol.ac.uk> wrote:
> Hi John,
> 
> I've just installed the latest version of desmat available on SSC -
> 
> Distribution-Date: 20011111. (I had the STB-61: dm73.3 version 
> before.)However an -exp- option still doesn't exist:
> 
> . desmat: logistic siweekT2 age10yy2, exp
> exp invalid
> r(198);
> 
> . which desmat
> c:\ado\stbplus\d\desmat.ado
> *! version 3.0, 30Mar2001, John_Hendrickx@yahoo.com
> 
> And I'm not including any continuous covariates - only a single
> categorical 
> one with 6 categories at present.  -desmat- takes around 2 minutes
> even if 
> I give an outcome variable that doesn't exist so that all it gives
> is an 
> error message to that effect.  (If given a non-existent covariate
> it 
> complains straight away though.)
> 
> I suppose I could drop all those variables corresponding to
> questions that 
> we're not using (data is results of a survey with a *long*
> questionnaire) 
> but that would be some extra work to create and maintain a 'keep
> list' of 
> variables I'm actually interested in.
> 
> Roger.
> 
> 
> --On 03 October 2002 04:33 -0700 John Hendrickx
> <john_hendrickx@yahoo.com> 
> wrote:
> 
> > Hi Roger,
> >
> > -desmat- should add a few seconds to your calculations but two
> > minutes is way too much. One explanation might be that a
> continuous
> > variable wasn't specified as such, then -desmat- will create
> dummies
> > for all 100+ categories and estimation will take a long time. Let
> me
> > know if -desmat- really slows things down that much on a large
> > dataset, maybe it would be worthwhile to create a lite version.
> >
> > As for exponential coefficients, use the -exp- option,
> >
> > desmat: logistic y x, exp
> >
> > will give the same results as
> >
> > xi: logistic y i.x
> >
> > -logistic- prints exponential coefficients but saves them as
> > loglinear values.
> >
> > Good luck,
> > John Hendrickx
> >
> > --- Roger Harbord <Roger.Harbord@bristol.ac.uk> wrote:
> >> What I was really after in the end was similar to the output of
> >> e.g.
> >> . xi: logistic y i.x
> >> . reformat, eform
> >>
> >> - but with the coefficients labelled using the value labels
> >> assigned to x.
> >> -desmat- does achieve this, but I had a couple of different
> >> problems when I
> >> tried -desmat-:
> >>
> >> 1) It takes over 2 minutes to run the first univariable logistic
> >> regression
> >> with -desmat- on my data , when -xi- is seemingly instant.  May
> be
> >> connected to the fact that my dataset has 1100 variables (and
> 2400
> >> observations).  Much quicker subsequently though, even run on
> >> different
> >> variables.
> >>
> >> 2) I can't see how to get -desmat- to exponentiate the
> coefficients
> >> (to
> >> give odds ratios with logistic regression) when used as a
> command
> >> prefix:
> >>
> >> . desmat: logistic y i.x
> >>
> >> gives the same output as:
> >>
> >> . desmat: logit    y i.x
> >>
> >>  - and there's no -eform- option as there is with -outreg- and
> >> -reformat-.
> >>
> >> Also I think -reformat- or -outreg- give me more flexibility in
> >> deciding
> >> what I want in the output, so I don't need to do so much work on
> >> the output
> >> before I present it to my client, which is ultimately my aim.
> >>
> >> In conclusion i'll probably use Nick's 'canned solution' for
> >> transferring
> >> value labels to variable labels of dummies, in combination with
> >> -reformat-
> >> or -outreg-.  But maybe it would be nice if there was an option
> for
> >> -xi- to
> >> tell it to inherit the labels in this way.  Put that on the wish
> >> list for
> >> Stata 8...
> >>
> >>
> >> Roger.
> >> ----------------------------------------------------
> >> Roger Harbord     mailto:roger.harbord@bristol.ac.uk
> >> Department of Social Medicine, University of Bristol
> >>
> >>
> >>
> >> --On 03 October 2002 09:33 +0100 Nick Cox <n.j.cox@durham.ac.uk>
> >> wrote:
> >>
> >> > John Hendrickx
> >> >
> >> >> -desmat- will do this. Try -ssc describe desmat-
> >> >
> >> > I tried -desmat- after my posting. I couldn't
> >> > see that it did quite this.
> >> >
> >> > Example:
> >> >
> >> >
> >>
> >
>
----------------------------------------------------------------------
> >> > -------------------------------------
> >> >        log:  C:\Stata7\desmat.log
> >> >   log type:  text
> >> >  opened on:   3 Oct 2002, 09:30:21
> >> >
> >> > . u auto
> >> > (1978 Automobile Data)
> >> >
> >> > . desmat : regress mpg foreign
> >> >
> >>
> >
>
----------------------------------------------------------------------
> >> > ---------
> >> >    regress
> >> >
> >>
> >
>
----------------------------------------------------------------------
> >> > ---------
> >> > < snip >
> >> >
> >>
> >
>
----------------------------------------------------------------------
> >> > ---------
> >> > nr Effect
> >> Coeff
> >> > s.e.
> >> >
> >>
> >
>
----------------------------------------------------------------------
> >> > ---------
> >> >    foreign
> >> > 1    Foreign
> >> 4.946**
> >> > 1.362
> >> > 2  _cons
> >> 19.827**
> >> > 0.743
> >> >
> >>
> >
>
----------------------------------------------------------------------
> >> > ---------
> >> > *  p < .05
> >> > ** p < .01
> >> >
> >> > . d _x_1
> >> >
> >> >               storage  display     value
> >> > variable name   type   format      label      variable label
> >> >
> >>
> >
>
----------------------------------------------------------------------
> 
=== message truncated ===


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