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Re: st: Concentration Curve and Index


From   TinnaLaufey Asgeirsdottir <statalist@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Concentration Curve and Index
Date   Mon, 5 Sep 2005 18:00:00 +0000

Thanks Roger,
I will try that
Tina

On 9/5/05, Roger Newson <roger.newson@kcl.ac.uk> wrote:
> At 15:36 05/09/2005, Tina wrote:
> >Hello Statalist
> >
> >I am looking at income inequalities in health and using the
> >concentration curve and concentration index (based on the Gini and the
> >Lorenz curve).
> >
> >I managed to draw a graph and calculated the index number. However I
> >know there must be a better way then mine since I do not get any
> >standard deviations or confidence intervals my way... others are
> >reporting those.
> >
> >(The way I did it was just by sorting by income, and adding % of total
> >population health cumulatively, starting from the least advantaged
> >individual based on family income. Then I drew a curve based on this
> >information. The index number is supposed to be twice the area between
> >the line of equality and the concentration curve.  For the Index I
> >simply calculated the difference between the curve i calculated and
> >the line of equality and doubled that number.  Basically, I just
> >worked my way to the answer through the theory behind the curve and
> >the index.)
> >
> >I haven't found one paper that describes how this was calculated,
> >which means it is probably so easy that it should be obvious. I have
> >looked all over older statalist mails and the Internet and am still in
> >the dark. Is there a regression involved that I do not know about? Do
> >any of you know it?
> >
> 
> 
> The -somersd- package, downloadable from SSC, can calculate confidence
> intervals for the Gini index, with the option of using the
> variance-stabilizing z-transformation. In Stata, type
> 
> ssc install somersd, replace
> 
> to install the latest Stata 9 version of -somersd-, and type
> 
> net get somersd
> 
> to copy the manuals -somersd.pdf- and -cendif.pdf- to your local folder.
> The manual -somersd.pdf- contains an example of the calculation of
> confidence intervals for Gini indices using -somersd-, and an explanation
> of why the Gini index is a special case of Somers' D.
> 
> I hope this helps.
> 
> Roger
> 
> 
> 
> --
> Roger Newson
> Lecturer in Medical Statistics
> Department of Public Health Sciences
> Division of Asthma, Allergy and Lung Biology
> 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://phs.kcl.ac.uk/rogernewson/
> 
> Opinions expressed are those of the author, not the institution.
> 
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