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Re: st: Dropping min of two consecutive observations


From   Jeph Herrin <junk@spandrel.net>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Dropping min of two consecutive observations
Date   Thu, 13 Nov 2008 16:42:50 -0500


. bys ID (month) : keep if _n==_N


should do it.



Rijo John wrote:
Dear Statalist,

 I have some repeated observations that I need to drop. I have defined
a unique ID variable. There are two other variables "value" and
"month" for these IDs.

Example data.

ID Value  month
1  25        12
1  22         8
2  30         9
3  28         8
3  24         6


Only few IDs are repeated in the actual data.

Basically I need to retain only one value per ID. If I do "drop if
ID==ID[_n-1]" after sorting the IDs it could drop any of the values.
But I want the data to retain those values where in month takes the
highest value when I am dropping ID==ID[_n-1].  Something like

drop min(month, month[_n-1]) if ID==ID[_n-1] is what I am looking for.
However, I cant use such time series operators with min function. Any
thoughts?

Regards,
Rijo.
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