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RE:st: ineqdeco by more than one subgroup, and error-thanks
Thanks very much. This is very helpful.
--- "Stephen P. Jenkins" <firstname.lastname@example.org> wrote:
> Date: Tue, 30 Aug 2005 02:05:30 -0700 (PDT)
> From: Brian Sartene <email@example.com>
> Subject: st: ineqdeco by more than one subgroup,
> and error
> Having used ineqdeco to identify the various
> components of inequality in my sample, I'd now like
> find out the joint impact of all my 'observable'
> components in explaining levels of between-group
> inequality (e.g., the joint impact of race, gender,
> educational attainment).
> I wonder if this is something ineqdeco permits?
> Also is it possible to calculate the error
> the between-group and within-group estimates?
> With many thanks.
> Qn 1.
> Regarding principles, you might like to look at:
> FA Cowell and SP Jenkins "How much inequality can we
> explain? A
> methodology and an application to the USA", Economic
> Journal 105(429),
> March 1995, pp. 421-430.
> We addressed the question that I think you wish to
> answer, and suggested
> methods that use statistics that can be estimated by
> BTW -ineqdeco- can produce subgroup decompositions
> where the subgroups
> are defined by more than one variable -- just put a
> varlist in the
> bygroup() option. [This has been mentioned on
> Statalist before; see the
> archives.] You don't get much control over the way
> the output appears,
> however, and so you may prefer to first use
> egen newvar = group(varlist)
> to create subgroups in a way that suits you best,
> and then use newvar in
> the bygroup() option.
> Qn 2.
> By "error", I presume that you mean "sampling error"
> -- you want
> standard errors for the components?
> The short answer is "no", though in principle one
> could. Be aware that
> this is a non-standard problem (made worse if there
> are sampling weights
> and you don't want to treat them as deterministic).
> Note e.g. that
> between-group inequality is a non-linear function of
> subgroup means,
> each of which is estimated. Within-group inequality
> is a weighted sum of
> subgroup inequalities where the weights and the the
> inequalities are
> estimated. I am aware of only one paper on this
> topic giving analytical
> expressions for the sampling variances (and in a
> simplified case) -- I
> think it was by Formby and collaborators in the
> Bulletin of Economic
> Research about 5 years ago.
> Perhaps the easiest way forward for now would be to
> bootstrap. To do
> this you would need to write a little program
> wrapper, defining an
> rclass program. With this program you would save the
> -ineqdeco- outputs
> you want as r() results. (NB -ineqdeco- is a version
> 5 program so you
> would refer to the saved results by putting a "$" in
> front of the
> relevant name: see help file, and Statalist
> archives.) And then you
> would bootstrap using the rclass program (for
> details, see Manuals)
> Stephen (author of -ineqdeco-)
> Professor Stephen P. Jenkins <firstname.lastname@example.org>
> Institute for Social and Economic Research
> University of Essex, Colchester CO4 3SQ, U.K.
> Tel: +44 1206 873374. Fax: +44 1206 873151.
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