topic Re: How to create a variable that contains the number of measurement of each subject? in SAS Programming

How to create a variable that contains the number of measurement of each subject?

Denali — Wed, 06 Jan 2021 04:46:20 GMT

Hi,

How do I create a new variable that contains the number of measurement of each subject?

In below case, subject ID#4 has 3 repeated measurements so 3 should be assigned to his/her number of measurement, and subject ID#7 had 2 repeated measurements so 2 should be assigned as the number of measurement, subject ID#1 has only 1 measurement so 1 should be assigned to the new variable.

Subject ID	measurement
1	1
2	1
3	1
4	1
4	2
4	3
5	1
6	1
7	1
7	2
8	1
9	1
10	1
11	1
12	1
12	2
13	1
13	2
14	1
15	1

Thank you in advance!

Re: How to create a variable that contains the number of measurement of each subject?

Norman21 — Wed, 06 Jan 2021 05:01:09 GMT

Something like this?

DATA have;
INPUT SubjectID measurement;
cards;
1 1
2 1
3 1
4 1
4 2
4 3
5 1
6 1
7 1
7 2
8 1
9 1
10 1
11 1
12 1
12 2
13 1
13 2
14 1
15 1
;
RUN;

PROC SORT DATA = have;
BY SubjectID;
RUN;

PROC PRINT;
RUN;


DATA want;
SET have;
BY SubjectID;
IF LAST.SubjectID;
RUN;

PROC PRINT;
RUN;

Re: How to create a variable that contains the number of measurement of each subject?

andreas_lds — Wed, 06 Jan 2021 06:17:36 GMT

Maybe creating the dataset you have could be avoided by using something like

proc summary data=original nway;
  class SubjectID;
  output out=measured(drop= _type_ rename=(_freq_=measurement));
run;

with the data used to create the dataset you have shown.