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st: RE: RE: Re: RE: RE: Continous to categorical variable


From   "Jason Yackee" <jyackee@law.usc.edu>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: RE: Re: RE: RE: Continous to categorical variable
Date   Wed, 21 Feb 2007 09:45:18 -0800

I would use standard deviations to create the categorical variable.  Say you wanted six categories -- "1" is greater than negative 2 stdev from the the mean, "2" is any observation between negative 1 and negative 2 stdev from the mean, 3 is between 0 and negative 1 stdevs, 4 is between 0 and positive 1 stdevs, and so on.

The only thing "by hand" is calculating the descriptive statistics, and recoding the variable six times.

Jason Webb Yackee
Fellow
Gould School of Law
University of Southern California
Los Angeles, California 90089-0071
Tel: 213-740-2865
Fax: 213-740-5502
Cell: 919-358-3040
email: jyackee@law.usc.edu
 


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Mentzakis, Emmanouil
Sent: Wednesday, February 21, 2007 9:33 AM
To: statalist@hsphsun2.harvard.edu
Subject: st: RE: Re: RE: RE: Continous to categorical variable

Yes, something like that would be nice but note that my continous
variable has 62,000 unique values so I cannot do them by hand.
 
Thank you
Manos 

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Sergiy
Radyakin
Sent: 21 February 2007 17:16
To: statalist@hsphsun2.harvard.edu
Subject: st: Re: RE: RE: Continous to categorical variable

Why would you want to do that?

Would this be something you are looking for?


------------------------------------------
input educ
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
end
hist educ,d
recode educ (1=1) (2 3=2) (4 5 6=3) (7 8 9 10=4) (11 12 13 14=5) (15 16
17=6) (18 19=7) (20=8),gen(educ2)
hist educ2,d
------------------------------------------

Now if you do:

scatter educ educ2

you will realize that you need to place the cut off points at the
quantiles of the normal distribution (transformed properly for your
data)



Sergiy








----- Original Message ----- 
From: "Mentzakis, Emmanouil" <e.mentzakis@abdn.ac.uk>
To: <statalist@hsphsun2.harvard.edu>
Sent: Wednesday, February 21, 2007 6:03 PM
Subject: st: RE: RE: Continous to categorical variable


> Maybe I should describe a little bit better.
>
> I do not want the variable to "become more like a normal
distribution".
> What I would like is the categories created to be such that the tails
> contain less individuals, with an increase in the numbers as we get
> closer to the middle category.
>
> Thanks
> Manos
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Maarten
Buis
> Sent: 21 February 2007 16:48
> To: statalist@hsphsun2.harvard.edu
> Subject: st: RE: Continous to categorical variable
>
> --- Mentzakis, Emmanouil wrote:
>> I have a continous variable (i.e. income) and I would like to
>> transform it into a categorical one (e.g 5 categories/levels or
more).
>>
>> I would like to ask if there is any way that I can ask stata to
create
>
>> this variable deciding the appropriate cut-off points automatically
so
>
>> that the categories follow aproximately a normal distrubution or they
>> are of equal size.
>
> For the latter have a look at -help egen- and look at the cut
function.
> For the former: how would you expect a variable to become more like a
> normal distribution by making it coarser?
>
> Hope this helps,
> Maarten
>
> -----------------------------------------
> Maarten L. Buis
> Department of Social Research Methodology Vrije Universiteit Amsterdam
> Boelelaan 1081
> 1081 HV Amsterdam
> The Netherlands
>
> visiting address:
> Buitenveldertselaan 3 (Metropolitan), room Z434
>
> +31 20 5986715
>
> http://home.fsw.vu.nl/m.buis/
> -----------------------------------------
>
>
>
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