Any answer is consistent as long as P(aliens in universe) > P(aliens in milky way), but the ratio implicitly depends on how densely populated you think the universe is conditional on aliens existing at all, assuming aliens are distributed randomly among galaxies.
Any answer is consistent as long as P(aliens in universe) > P(aliens in milky way), but the ratio implicitly depends on how densely populated you think the universe is conditional on aliens existing at all, assuming aliens are distributed randomly among galaxies.