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Re: st: How do I make frequencies for combined variables?


From   Sergiy Radyakin <serjradyakin@gmail.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: How do I make frequencies for combined variables?
Date   Wed, 26 Jun 2013 16:36:57 -0400

" need the frequency of each of them them of combination of two then
the three of them."
this will be a lot of combinations for 12 symptoms: 2^12 if I am not
mistaken? 4096
Perhaps listing just the combinations that occur in your data would
suffice? The rest you would know are zeroes.
See below for a starter.

Best, Sergiy Radyakin


sysuse auto, clear

gen s1=(mpg>16)
gen s2=(mpg>20)
gen s3=s2|foreign
gen s4=price<5000&!foreign

local symptoms "s1 s2 s3 s4"

egen sg=group(`symptoms')
tabulate sg
keep sg `symptoms'
sort sg
preserve
quietly by sg : keep if _n==1
list sg `symptoms', clean noobs
restore


On Wed, Jun 26, 2013 at 4:08 PM, Edouard Betsem <edouardbetsem@gmail.com> wrote:
> Dear Statalisters,
> I am new in Stata and currently working on symptoms combinations for a
> specific disease.
> There are 12 symptoms that can be found in combinations of 1 to 12 in
> different individuals (cases and controls)
> I would like to tell how frequent any combination is in disease negative
> individuals.
> I need to list specifically the symptoms in any combination and the
> frequency of that particular combination.
>
> If I consider fever, headache and cough,
> i need the frequency of each of them them of combination of two then the
> three of them.
> thank you for your great help
> Edouard
>
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