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RE: st: Ranking observations within groups


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Ranking observations within groups
Date   Thu, 11 Dec 2008 19:28:02 -0000

Despite your positive reply, I don't believe that is what you want. 

webuse machine 
bysort machine (output) : gen rank = output != output[_n-1]
by machine : replace rank = sum(rank)

seems to be what you are asking for. 

Nick 
n.j.cox@durham.ac.uk 

James Cross

Great, thanks!

2008/12/11 David Airey <david.airey@vanderbilt.edu>:

> Seems the unique option does what you describe you need.
>
> clear
> webuse machine.dta
> drop operator
> bysort machine: egen rank = rank(output)
> bysort machine: egen rankf = rank(output), field
> bysort machine: egen rankt = rank(output), track
> bysort machine: egen ranku = rank(output), unique
> sort machine output
> list, clean

> On Dec 11, 2008, at 9:04 AM, James Cross wrote:

>> I have a variable that represents different actors positions on
>> different issues (groups). So I have around 30 positions between 0
and
>> 100 for each individual issue within the variable with quite a few
>> ties. I want to create a variable that ranks these observations in
>> ascending order so that the lowest observation(s) will have a value
of
>> 1 in the new variable, the second lowest observation(s) will have a
>> value of 2 and so on.
>>
>> I have tried -by issue_var: egen newvar = rank(oldvar), track- but
>> this returns a newvar in which the lowest variable is given 1st
>> position, which is fine, but if there are say 3 ties for position 1,
>> the second lowest oldvar is ranked in 4th position rather than 2nd
>> position which is what I need. Any ideas as to how I could create a
>> newvar where ties do not change the rank position of following
>> observations within each group?

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