THC level to plant material, that is your potency ratio. So, if either the THC level goes up, or the plant material goes down, potency increases.

Example. If you and your friend had the same tolerance to weed, and had 2 of the exact same bowls, and you fill yours with water cured grass, and they fill theirs with air cured grass, and you both smoke it til it's completely cashed, then you would be higher than your friend.

I hope this will get rid of all the confusion over that.