Even though there is no function is available in SAS to do exactly the opposite work of the LAG function (i.e: reading the next record while working on the current one), there are few things you can do to do exactly that.
Here are few simple techniques which are proved to work without any problem.
*SAMPLE DATASET;
data test;
input id age grp ;
datalines;
1 10 1
2 20 1
3 30 1
4 40 1
5 50 1
1 10 2
2 20 2
3 30 2
4 40 2
5 50 2
;
run;
*1) Using the POINT feature along with automatic variable _N_;
This solution was suggested by Paul M. Dorfman;
data leads;
_n_ ++ 1;
if _n_ le n then do;
set one point=_n_;
leadage=age;
end;
set one nobs=n;
run;
*OR*;
data leads;
_n_ ++ _n_ lt n;
set one point=_n_;
leadage=age;
set one nobs=n end=end;
if end then leadage=.;
run;
By using the above techniques, you can jump a bit higher and even look values of two, three or any numbers of observations in advance by advancing the value of automatic variable _N_ by appropriate number (in general _N_ ++ n ). Only thing you have to keep in mind while doing so is before applying the POINT processing, you have to apply appropriate lag (lagn) to grouping variable.
References:
SAS-L. http://www.listserv.uga.edu/cgi-bin/wa?A2=ind9904E&L=sas-l&P=R6185
http://www.nesug.org/Proceedings/nesug09/cc/cc26.pdf
Option3:
option mergeNoBy=nowarn; *Supress the warning message in the log. WARNING: No BY statement was specified for a MERGE statement.;
data lead;
merge one one(firstobs = 2 rename=(age=leadage));
run;
