topic Re: split data in tow equal group in SAS Procedures

split data in tow equal group

sasphd — Tue, 24 Jan 2023 15:51:29 GMT

Hello

I have 92 funds in my database. they are sorted by PCSSP_median. I want to split them in two group (46 low_median and 46 high median). I write this but it does not make equal division


 proc rank data=PCSSP_sort out=want groups=2;
var PCSSP_median;
ranks deciles;
run;

thanks

Re: split data in tow equal group

PaigeMiller — Tue, 24 Jan 2023 15:52:57 GMT

PROC RANK will not make groups of equal size when there are ties in the data. So, if you still want equal sizes, you'd have to write code yourself to split up the ties, some into group 1 and some into group 2.

Re: split data in tow equal group

ballardw — Tue, 24 Jan 2023 17:54:53 GMT

Crude:

Proc sort data=pcssp_sort;
   by pcssp_median;
run;

data want;
   set pcssp_sort;
   group= (_n_ le 92)+1;
run;

Assigns group 1 for smaller values, 2 for larger. May have same value of pcssp_median in both groups depending on where ties in your data occur.

Re: split data in tow equal group

Reeza — Tue, 24 Jan 2023 18:00:16 GMT

Deciles are groups of percentiles, broken into 10's. Since you're grouping by 2 I would not recommend naming them deciles to avoid confusion.
If there are ties then PROC RANK will allocate into the same group - what do you want to happen if there are ties?

data want;;
set PCSSP_sort nobs=_nobs;
RANK = 1 - ( _n_ < (_nobs/2));
run;

Quick brute force method above.

NOBS captures the number of observations in the dataset.

NOBS/2 is the middle.

0 => low_median

1 => high_median

If you want it split by the median, PROC RANK is correct.