first visit of id_no

[Davidliu494]

data have;

  input id_no visit measurement;

  cards;

11 1 110

11 1 120

11 1 115

11 2 90

11 2 89

22 1 80

22 1 95

22 2 90

22 2 90

22 2 95

26 1 65

33 1 95

33 1 95

;

run;

for each visit, we take multiple measurement of the patient. we need to find the average of these measurements for each visit.

I run into problem trying to get the first or last visit for the same idno. so the expected output is:

11 1 115

11 2 89.5

22 1 88.3

etc...

[Haikuo · Accepted solution]

There will be many many ways to do it. The least mind-twisting method (may not be the fastest) is SQL:

proc sql;

   select id_no, visit, avg(measurement) as avg_m from have group by id_no, visit;quit;

Haikuo