Not OP, but I would say that when statistics acts like a subfield of mathematics, then it is an art. However, if we consider judging whether a statistical meth

Not OP, but I would say that when statistics acts like a subfield of mathematics, then it is an art. However, if we consider judging whether a statistical method will be useful for the world as a part of statistics, then that part sometimes is an empirical science. That is, the statement "I should use X technique because it performs Y% well" is sometimes an an empirical statement.