Checking How Many Participants have a certain number of visits

[zaldarsa]

Hi!

I want see how many individuals in my data set  have visits 1-7, how many have visits 1-8, and how many have visits 1-9. What would be an efficient way to go about doing this? Thank you all in advance for your help.

[PaigeMiller]

Can you show us a portion of your data so we can understand what the data looks like?

[zaldarsa]

Sure. So here is an example of what my data looks like, except my dataset has around 400 observations.

ID       Visit
1            1
1            2
1            3
2            1
3            1
3            2
3            3
3            4
3            5
3            6
3            7
4            1
4            2
4            3
5            1
5            2
5            3
5           4
5           5
5           6
5           7
5           8
6            1
6           2
6           3
6           4
6           5
6           6
6           7
6          8
6           9

[Reeza]

Assuming your data is always consecutive you only need the last for each ID really. 

*get maximum per ID;
proc sql;
create table id_max as
select id, max(visit) as max_visit from have;
quit;

*check distribution;
proc freq data=id_max;
table max_visit;
run;

---

@zaldarsa wrote:

Sure. So here is an example of what my data looks like, except my dataset has around 400 observations.

ID       Visit
1            1
1            2
1            3
2            1
3            1
3            2
3            3
3            4
3            5
3            6
3            7
4            1
4            2
4            3
5            1
5            2
5            3
5           4
5           5
5           6
5           7
5           8
6            1
6           2
6           3
6           4
6           5
6           6
6           7
6          8
6           9

---

[PaigeMiller]

So is it valid to assume that the numbers in the VISIT column are always consecutive within an ID? That the numbers in the VISIT column never repeat or skip?

[zaldarsa]

They are in order, but i didn't double check my data, and it does indeed skip, but no repeat. For example, visit 3 may not be there for some people.

[PaigeMiller]

Well don't leave us in suspense. What happens to an ID that doesn't have Visit 3 but has 1, 2, 4, 5, 6? Is that the 1-6 category? Or do you want it to be categorized some other way?

[zaldarsa]

I apologize for my lack of clarity. It would still be visit 1-6 regardless of what is missing in between, so I would still apply a similar code as if it were consecutive , in that case, correct?

[PaigeMiller · Accepted solution]

proc summary data=have nway;
    class id;
    var visit;
    output out=stats max=max_visit;
run;