topic Re: How to create variable block size in randomization in sas in SAS Programming

How to create variable block size in randomization in sas

Lidia1 — Thu, 05 Nov 2020 12:08:08 GMT

I want to create a variable block size in randomization in sas.Block size will be multiple of 8 (3:1:3:1). It will look like something like below (In the example we have 8 obs for block 1,8 obs for block 2,16 for block 3,24 for block 4)

var1	block	var2	var3
1	1	L	1
2	1	L	1
3	1	L	1
4	1	L	1
5	1	L	1
6	1	L	1
7	1	L	1
8	1	L	1
9	2	L	1
10	2	L	1
11	2	L	1
12	2	L	1
13	2	H	1
14	2	L	1
15	2	L	1
16	2	L	1
17	3	L	1
18	3	H	1
19	3	L	1
20	3	L	1
21	3	L	1
22	3	L	1
23	3	H	1
24	3	L	1
25	3	L	1
26	3	L	1
27	3	L	1
28	3	L	1
29	3	L	1
30	3	L	1
31	3	L	1
32	3	L	1
33	4	L	1
34	4	L	1
35	4	L	1
36	4	L	1
37	4	L	1
38	4	L	1
39	4	L	1
40	4	L	1
41	4	L	1
42	4	L	1
43	4	L	1
44	4	L	1
45	4	L	1
46	4	L	1
47	4	L	1
48	4	L	1
49	4	L	1
50	4	L	1
51	4	L	1
52	4	L	1
53	4	L	1
54	4	L	1
55	4	L	1
56	4	L	1

Re: How to create variable block size in randomization in sas

PaigeMiller — Thu, 05 Nov 2020 12:37:30 GMT

Do you want code that is dynamic and figures out the block size? Or do you want to just hard-code 8 8 16 24?

Re: How to create variable block size in randomization in sas

Lidia1 — Thu, 05 Nov 2020 12:39:39 GMT

I need a dynamic code that will return the block size as multiple of 8 (random).

Re: How to create variable block size in randomization in sas

PaigeMiller — Thu, 05 Nov 2020 12:45:16 GMT

UNTESTED CODE

proc summary nway data=have;
    class block;
    var var1;
    output out=block_size n=block_size;
run;
data want;
     merge have block_size;
     by block;
run;

There's nothing here that forces the block size to be a multiple of 8, it just computes the number of records in each block.

Re: How to create variable block size in randomization in sas

Shmuel — Thu, 05 Nov 2020 12:57:17 GMT

Do you have a dataset and you want just to generate the BLOCK variable or

do you want to generate the whole dataset?

You can use RANUNI function or any other randomization sas function in order to

define the block size, something like:

retain block_size;
block_size = int(ranuni(-1) * 80); /* any value in range 1-80 */
do i=1 to block_size;
     /* any other computation, assiging value to variables */
    OUTPUT;
end;

Insert that code in the data step - either to generate a new dataset or to add observation to a given one.

Re: How to create variable block size in randomization in sas

Shmuel — Thu, 05 Nov 2020 12:59:17 GMT

Check also :
https://communities.sas.com/t5/SAS-Programming/Query-on-auto-generation-of-variable-and-data/m-p/696797#M212900