topic Re: Set value at one time point to all time points for each participant in SAS Programming

Set value at one time point to all time points for each participant

keherder — Fri, 10 Dec 2021 05:40:48 GMT

Hello!

Wondering if anyone could help me with this. Here is a photo of my data set:

We are assuming that the heights stay the same for each visit. What I would like to do is fill in the missing height values with the value for visit 1 for the rest of the visits for each participant. For example, the height of participant 1484 was 196 at visit 1. I would like to replace the missing values for visits 2-6 with 196 for this participant and do the same for all participants. Does anyone know how I can code this?

Thank you so much!

Re: Set value at one time point to all time points for each participant

japelin — Fri, 10 Dec 2021 05:54:16 GMT

You can use retain statements to achieve this, but if you need specific code, please provide the data in a usable form, not as an image.

Maybe the code is something like this. (I haven't tested it because I don't have the data)

data want;
  set biosd.lab_wide;
  by caseid;
  retain height;
  if first.caseid then height=height_cm_;
  else height_cm_=height;
  drop height;
run;

Re: Set value at one time point to all time points for each participant

andreas_lds — Fri, 10 Dec 2021 06:22:11 GMT

Imho the else-part needs an update:

else do;
  if missing(height_cm_) then do;
    height_cm_ = height;
  end;
end;

or shorter

else do;
  height_cm_ = coalesce(height_cm_, height);
end;

Re: Set value at one time point to all time points for each participant

ballardw — Fri, 10 Dec 2021 08:04:18 GMT

What if the first visit does not have a measurement?

Have you verified that none of your Caseids have more than one measurement that is not unique? Children over a period of 5 or 6 months may well show a change in height.

Re: Set value at one time point to all time points for each participant

keherder — Fri, 10 Dec 2021 16:32:13 GMT

Good point! This is just a simulated data set, however, for a classroom project and we were told to assume heights stayed constant.