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# RE: st: Combinations of variables

 From "Seliger Florian" To "statalist@hsphsun2.harvard.edu" Subject RE: st: Combinations of variables Date Tue, 4 Jun 2013 15:34:49 +0000

```Thank you Nick, that helped a lot.

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox
Sent: Dienstag, 4. Juni 2013 16:21
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: Combinations of variables

There are several ways to get at this. One I like, for reasons easy to infer, is to use -groups- from SSC. The example here uses just two categorical variables, but having more variables is fine, just messier.

. sysuse auto, clear
(1978 Automobile Data)

. groups foreign rep78

+------------------------------------+
|  foreign   rep78   Freq.   Percent |
|------------------------------------|
| Domestic       1       2      2.90 |
| Domestic       2       8     11.59 |
| Domestic       3      27     39.13 |
| Domestic       4       9     13.04 |
| Domestic       5       2      2.90 |
|------------------------------------|
|  Foreign       3       3      4.35 |
|  Foreign       4       9     13.04 |
|  Foreign       5       9     13.04 |
+------------------------------------+

Note that -contract- would give you an easy answer, at the cost of destroying the dataset.

Nick
njcoxstata@gmail.com

On 4 June 2013 15:14, Seliger  Florian <seliger@kof.ethz.ch> wrote:

> I need to find the most frequent combinations of variables in my dataset.
> There are 12 variables of interest each coded 0/1.
>
> Example:
>
> ID           var1       var2       var3 ..
> 1             0             1             0
> 2             0             0             1
> 3             0             1             0
> 4             1             1             1
> 5             0             1             0
> .
> .
> .
>
> In this example, the most frequent combination is var1=0, var2=1, var3=0 (for ID 1, 3, 5).
>
> At the moment, I have no idea how to find out the combinations for so many different cases automatically.
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```