I think there are some serious semantical problems going on between the OP and everyone else here.
Hit chance = chance for YOUR CHAR to hit your opponent
Miss chance = chance for your char to miss hitting your opponent
CHANCE TO BE MISSED = your chance to be missed which is 5% default + what you gain from defense (which has diminishing returns mind you)
CHANCE TO BE HIT = your chance to be regularly hit by a mom, this is normally taken by subtracting your combined avoidance+block from the boss' attack table.
If you're going to post on tankspot, you need to use the terminology here, or at least explain your own terminology. You can't expect us to simply "know" what you're referring to, when the terms are confusing from site to site. we have our own syntax for words here, and it's often accepted as the standard since we ARE the frontline of tanking information. Please, stop, calm down, and rethink your original question, and post it, as best as you can, explaining everything that may be misconstrued. Otherwise, this thread will be closed shortly, because frankly, I'm tired of seeing back and forth arguments of EHP vs Avoidance or EHP vs Threat stats where neither side is going to budge, and no real math is being presented by 1 or both sides.