Re: st: RE: Dividing data into quintiles

[Clarice Martins <martins.clarice@gmail.com>]

Hello David, hello all!!

I believe you understood correctly!  Thank you for your suggestion!

But forgive me, if I am totally off, I am very new with Stata: I think I understood your code, but after creating the variable quintile, this one was kept empty. Should I see values recorded on that? Or the results of the code are stored virtually?   (sorry! very basic question!)

In my research, the next step will use returns for the companies in the 1st and 5th quintile of each  -rtype=="formation" & yrmonth == "`lev'"-  for calculations, so I do need to have available these quintiles (specifically 1st and 5th) for next step.

Thank you!!
Clarice



On Oct 28, 2013, at 4:58 PM, Radwin, David wrote:

> Clarice,
> 
> If I understand correctly, you merely need to loop through each value of yrmonth and calculate quintiles for observations with that value for yrmonth. But you can't generate a new variable 151 times. 
> 
> So you could do something this that creates quintiles for a temporary variable:
> 
> gen quintile = .
> quietly levelsof yrmonth, local(levs)
> foreach lev of local levs {
> 	tempvar quint
> 	xtile `quint' = return if rtype=="formation" & yrmonth == "`lev'", n(5)
> 	replace quintile = `quint' 
> 	}
> 
> 
> David
> --
> David Radwin
> Senior Research Associate
> Education and Workforce Development Division
> RTI International
> 2150 Shattuck Ave., Suite 800
> Berkeley, CA 94704
> Phone: 510-665-8274
> 
> www.rti.org
> 
> 
>> -----Original Message-----
>> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-
>> statalist@hsphsun2.harvard.edu] On Behalf Of Clarice Martins
>> Sent: Monday, October 28, 2013 11:39 AM
>> To: statalist@hsphsun2.harvard.edu
>> Subject: st: Dividing data into quintiles
>> 
>> Dear group,
>> 
>> I need to select a sub-group of my dataset and cut it into quintiles, in
>> order to proceed with calculations with top and bottom quintile.
>> 
>> - I use Stata 12.1 (for Mac)
>> 
>> - my data looks like this (now, after considerations from the group, thank
>> you!)
>> 
>> co_id ticker rtype	yrmonth return
>> 1 ABCB formation jun2000 0.01
>> 1 ABCB buysell jul2000 0.01
>> 1 ABCB holding ago2000 0.01
>> 2 AEDU formation jun2000 0.01
>> 2 AEDU buysell jul2000 0.01
>> 2 AEDU holding ago2000 0.01
>> 3 AMBV formation jun2000 0.01
>> 3 AMBV buysell jul2000 0.01
>> 3 AMBV holding ago2000 0.01
>> 
>> - i tryed both -egen cut- and -xtile-
>> 
>> egen quintile = cut(return) if rtype=="formation", group(5)
>> 
>> xtile quintile=return if rtype=="formation", n(5)
>> 
>> - when I use -if rtype=="formation"- both commands work fine!
>> 
>> - But, I need to select all observations rtype=="formation"  AND
>> yrmonth=="jun2000", then cut this subgroup into quintiles
>> 
>> - Then, I need to proceed with this filter/select and cut, for every
>> yrmonth (151 periods) on my data set
>> 
>> Any suggestions?
>> 
>> Thank you very much!
>> 
>> Clarice
> 
> 
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