after a procedure executes. Thus, @code{LAG} will not return values
from cases dropped by transformations such as @cmd{SELECT IF}, and
transformations like @cmd{COMPUTE} that modify data will change the
after a procedure executes. Thus, @code{LAG} will not return values
from cases dropped by transformations such as @cmd{SELECT IF}, and
transformations like @cmd{COMPUTE} that modify data will change the