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st: How to calculate 75 percentile of other individuals on the samegroup


From   Joseph Coveney <jcoveney@bigplanet.com>
To   Statalist <statalist@hsphsun2.harvard.edu>
Subject   st: How to calculate 75 percentile of other individuals on the samegroup
Date   Sat, 29 Sep 2007 14:57:11 -0700

Quang Nguyen wrote:

A simplified version of my data looks as follows:

ID      Group     X
1       a             5
2       a             7
3       a             9
4       a             8
5       b             3
6       b             4
7       b             9
..........................

I would like to generate a new variable whose value is the 75 percentile of
other individuals in the same group as the concerned individual. For
example, for the first individual (ID=1), this will be: 75 percentile
of {7, 9, 8}.

I would highly appreciate if someone could suggest me a solution for this.

--------------------------------------------------------------------------------

-findit percentile- turns up a lot to pore over.  But among the results
is -egen <varname> = pctile(exp), p(#)-, which can take a -by- varlist.

Try something like:
bysort Group: egen p75 = pctile(X), p(75)

Joseph Coveney


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