current one. Results in system-missing (for numeric variables) or
blanks (for string variables) for the first @var{n} cases.
-@code{LAG} obtains values from the cases that become the new active file
+@code{LAG} obtains values from the cases that become the new active
+dataset
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