06-15-2016 12:21 AM
I have a longituidnal data (Called as SBP & DBP which are contineous variables)- which is collected on different dates and the date variable looks like 10SEP2010. I have sample ID for each patient.
I would like to classify first measurement of SBP, DBP of each observation into one dataset and last measurement of SBP, DBP of each observation into another dataset.
How can I do this?
06-15-2016 01:18 AM
Browse source dataset by patient_ID and sampling_date. Output first record of a group to one dataset and the last to another. something like code below.
data destination_dataset1 destination_dataset2;
by patient_id sampling_date;
if first.patient_id then output destination_dataset1;
if last.patient_id then output destination_dataset2;
06-16-2016 02:57 AM
I'm trying to computete the difference between first and last observations. Can someone tell me why I have the following note?
06-16-2016 03:54 AM
"first" / "last" refer to a subgroup which means ordering. Your code does not browse the data set in an ordered manner (you should have a "by ... " clause in it.
I'd suggest you should read a little bit the basics to understand the mechanisms behind: