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 <[email protected]> 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:[email protected]
> Department of Social Medicine, University of Bristol
>
>
>
> --On 03 October 2002 09:33 +0100 Nick Cox <[email protected]>
> 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
> >
>
----------------------------------------------------------------------
> > ---------
> > _x_1 byte %8.0g foreign==1
> >
> >
> > . tab foreign
> >
> > Car type | Freq. Percent Cum.
> > ------------+-----------------------------------
> > Domestic | 52 70.27 70.27
> > Foreign | 22 29.73 100.00
> > ------------+-----------------------------------
> > Total | 74 100.00
> >
> >
> > That is, the variables created do not inherit value labels,
> > which I understood be what Roger wanted.
> >
> > Nick
> > [email protected]
> >
> > *
> > * For searches and help try:
> > * http://www.stata.com/support/faqs/res/findit.html
> > * http://www.stata.com/support/statalist/faq
> > * http://www.ats.ucla.edu/stat/stata/
>
>
> *
> * For searches and help try:
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> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
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