st: Re: parmby & Beta

[Roger Newson <roger.newson@kcl.ac.uk>]

At 09:17 15/07/03 -0500, Fred Wolfe wrote:
> Is there anyway to get -parmby- output to include beta (Beta), as in:
>
>  parmby "reg cutdown high pain_ haq_ depress glb  age sex edlevel white 
> inctouse duration, beta", saving(testme, replace) for(estimate min95 
> max95 %8.2f p %8.1e) li(*)
This is not a simple thing to do, because -regress- does not save any such 
estimation result as -e(Beta)-. However, you could always standardise your 
Y- and X-variables before doing your regression, as in the following program:

foreach X of var cutdown high pain_ haq_ depress glb  age sex edlevel white 
inctouse duration {
  summ `X'
  replace `X'=(`X'-r(mean))/r(sd)
}
parmby "reg cutdown high pain_ haq_ depress glb  age sex edlevel white 
inctouse duration, beta", saving(testme, replace) for(estimate min95 max95 
%8.2f p %8.1e) li(*)

This would code all your Y- and X-variables to a scale of SDs from the 
mean, causing -estimate-, -min95- and -max95- to be expressed in Y-axis SDs 
per X-axis SD. To eliminate missing values listwise, you might type instead:

gene byte listmiss=0
foreach X of var cutdown high pain_ haq_ depress glb  age sex edlevel white 
inctouse duration {
  replace listmiss=1 if missing(`X')
}
foreach X of var cutdown high pain_ haq_ depress glb  age sex edlevel white 
inctouse duration {
  replace `X'=. if listmiss
  summ `X'
  replace `X'=(`X'-r(mean))/r(sd)
}
parmby "reg cutdown high pain_ haq_ depress glb  age sex edlevel white 
inctouse duration, beta", saving(testme, replace) for(estimate min95 max95 
%8.2f p %8.1e) li(*)

This would recode all your X- and Y-variables to missing in observations 
where any of the variables were previously missing, or to a scale of SDs 
from the mean otherwise, where the SDs and means are from observations not 
deleted listwise.

I hope this helps.

Roger


--
Roger Newson
Lecturer in Medical Statistics
Department of Public Health Sciences
King's College London
5th Floor, Capital House
42 Weston Street
London SE1 3QD
United Kingdom

Tel: 020 7848 6648 International +44 20 7848 6648
Fax: 020 7848 6620 International +44 20 7848 6620
  or 020 7848 6605 International +44 20 7848 6605
Email: roger.newson@kcl.ac.uk
Website: http://www.kcl-phs.org.uk/rogernewson

Opinions expressed are those of the author, not the institution.

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