Hello,
I have a clinical trial dataset and am trying to determine the frequencies of a few categorical variables as well as the number of unique patients per study arm at baseline.
I had initially done proc freq, but since I have multiple rows for each patient due to multiple visits per patient I was told that for proc freq there should only be one row/person. So, the values I got were a count of the same patient numerous times. I was told that I could use the where statement to only get the frequency at the baseline visit, but that did not work either. No observations were read.
My code is below:
proc freq data=xxxxl;
where visit="001";
tables race*group sex*group /norow nopercent;
run;
I received the following message in the log: NOTE: No observations were selected from data set xxx.
NOTE: There were 0 observations read from the data set xxx.
WHERE visit='001'
I am not sure what I did wrong and what I need to do to get the correct answer.
I am expecting the output to look as follows:
Group 1 Group 2
xxx xxx (these numbers would the number of unique patients in each group)
Race Group 1 Group 2
White xxx xxx
Black xxx xxx
Other xxx xxx
Any help would be greatly appreciated.
Thanks
Assuming your data is sorted by some patient_Id variable, try keeping the first record for each patient:
data patients;
set xxxxl;
by patient_Id;
if first.patient_Id;
run;
proc freq data=patients;
tables race*group sex*group /norow nopercent;
run;
Visit is a character variable?
Then do a proc freq of visit to see what values it actually has in the data step.
And also note;
where visit='001' will NOT match a right-justified 4-byte visit value of ' 001' (note leading space). If that's the problem, then either
where visit=' 001'
or
where left(visit)='001'
If you get fewer "001.00" cases than expected, then perhaps the original visit coding has errors or incosistencies. I think you have to find a patient with no visit="001.00" to see whether there are other codes indicating baseline visit.
Assuming your data is sorted by some patient_Id variable, try keeping the first record for each patient:
data patients;
set xxxxl;
by patient_Id;
if first.patient_Id;
run;
proc freq data=patients;
tables race*group sex*group /norow nopercent;
run;
Available on demand!
Missed SAS Innovate Las Vegas? Watch all the action for free! View the keynotes, general sessions and 22 breakouts on demand.
Learn how use the CAT functions in SAS to join values from multiple variables into a single value.
Find more tutorials on the SAS Users YouTube channel.