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Re: st: question on bootstrapping of proportions


From   Ernest Berkhout <Ernest.Berkhout@seo.nl>
To   statalist@hsphsun2.harvard.edu, statalist@hsphsun2.harvard.edu
Subject   Re: st: question on bootstrapping of proportions
Date   Fri, 18 Mar 2005 11:49:16 +0100

At 11:31 18/03/2005, Gijs Dekkers wrote:
Now a classical poverty measure quite popular here in Europe is the headcount ratio. One is poor if one's income is below 60 percent of the median income. In stata-syntax

by jaar: summarize income [aweight=weight],detail
by jaar: gen byte poor=income < 0.6*r(p50)
by jaar: tabulate poor [aweight=weight]
For someone using Stata for only 4 days, you're already quite advanced in your code! :-)
The only problem is that the above does not do what you want. The 'r(p50)' is a very temporary thing, and it gets overwritten immediately when you do another summarize. So in practice, you are referring to the median of the last year in your dataset.

I think you want something like:

local beginjaar = 1994
local eindjaar = 2002
foreach jaar = `beginjaar' / `eindjaar' {
summarize income [aweight=weight] if jaar==`jaar',detail
gen byte poor=income < 0.6*r(p50) if jaar==`jaar'
tabulate poor [aweight=weight] if jaar==`jaar'
}

Now you use the r(p50) reference to the median DIRECTLY in your calculation.



Ernest Berkhout
SEO Amsterdam Economics
University of Amsterdam
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