Re: st: question on bootstrapping of proportions

[Ernest Berkhout <Ernest.Berkhout@seo.nl>]

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
******************************************************
For information on flexwork & research: www.tempworkresearch.nl 
******************************************************
Room 3.08
Roetersstraat 29
1018 WB Amsterdam
The Netherlands

tel.:+ 31 20 525 1657
fax:+ 31 20 525 1686
http://www.seo.nl
===========================
A statistician: someone who insists
on being certain about uncertainty
=========================== 
*
*   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/