I have a four very big (500 000+ observations) dataset. They all have the same variables but are from different years.
what happens when I use a merge statement to merge them.
like:
data DRGa;
merge DRG2014a DRG2015a DRG2016a DRG2017a;
by pnr;
run;
my worry is that data will disappear if there are repeated observations in the same variable.
for instance date of hospitalization. For some it might only have happened in 2014 but for some it might have happened several times.
I guess I am wondering what happens to the data if there is repetetive observations over the years?
and if there is a better way to manage it?