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# Re: st: Quintiles

 From Maarten Buis To statalist@hsphsun2.harvard.edu Subject Re: st: Quintiles Date Thu, 9 Aug 2012 10:16:23 +0200

```On Wed, Aug 8, 2012 at 9:44 PM, Leonardo Jaime Gonzalez Allende wrote:
> I don't was planning to cut a person or household in many parts. The question was about a possible adjustment to the weight factor, if the observation of the sample is the cut point of the quintile.
>
> If I sort the households of a sample by their incomes, a household "x" could represents 300 households but the accumulated frequency of the population is e.g. 20,02%.
>
> My question was if there is an efficient way (command) to repeat the observation and adjust weight factor as follow:
>
> the same household "xa" now represents 280 households and now the accumulated frequency of the population is e.g. 20% (exactly) (leaving to the first quintile).

What kind of weight did you have in mind, aweigths, pweights,
iweights, fweights? Weighting can be a remarkably tricky issue. There
are many ways such a procedure could go wrong, and I don't know if
there is way to get it right. Anyhow, I cannot imagine a situation
where such an effort would be worth the cost (but that may just as
well say something about a lack of imagination on my part). I would
just live with the fact that the discrete nature of the number of
observations leads to slight variations in group size.

Did you look at the possibility that ties (different people reporting
exactly the same income) are the source of differences in group size?
In theory, such ties should be pretty rare for a (semi-)continuous
variable like income. However, in practice respondents tend to round
their answers, making such ties a lot more common.

-- Maarten

---------------------------------
Maarten L. Buis
WZB
Reichpietschufer 50
10785 Berlin
Germany

http://www.maartenbuis.nl
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