# st: Re:groups of pairs of variables

 From "Victor M. Zammit" <[email protected]> To <[email protected]> Subject st: Re:groups of pairs of variables Date Fri, 4 Jan 2008 19:40:44 +0100

```Dear Statalist,

I have twenty four variables namely 1 , 2, 3, ...,24,and I need to pair each
and every variable with each

one of the other twenty three variable such that I have the following 276
pairs of variables : 1    2,1   3,1   4,

...,1    23, 1    24, 2    3, 2    4, ..., 2    24, 3     4,..., 3     24,4
5,....,4     24,5      6, .......,.......,23     24.

I have managed to do this task with the help of the following code :

drop _all

set obs 576

gen a = .

gen b = .

gen n = .

local i = 1

while `i'<= 24 {

local u = 1

while `u'<= 24 {

local a = [`i'-1]*24 + `u'

replace a = `i' in `a'

replace b = `u' in `a'

replace n = `a' in `a'

local u = `u'+1

}

local i = `i'+1

}

drop if a>=b

What I need to do is to separate these 276 pairs of variables into 23 groups
,each group containing 12 pairs of

variables whereby no variable may repeat itself in any one group.Example:

1    2 , 3    4, 5    6, 7    8 , 9    10, 11    12 , 13    14 , 15    16
,17    18 , 19   20 , 21    22 , 23    24

1    3 , 2    4, 5    7, 6    8 , ..........
..............................                         ..............., 22
24

.................

.................

1   13, 2    14, .............                .......................
...............            ......., 11     23, 12      24

Can anyone please indicate any code that I can use so that I may not have to
do such an arduous process

by hand,especially when the number of variables is bigger ?

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```