Interesting question.
I'd say no you don't roll a miss chance on a confirmation of critical hit roll.
Here is why. . .
pg 140 of PHB "To find out it it's a critical hit, you immediately make a critical roll-another attack roll with all the same modifiers as the attack roll you just made."
Now this isn't another attack it is a confirmation roll (which is the key here IMO). The character is not spending an attack to make the confirmation roll he his just rolling for effect. Basically if the character has 2 attacks a round then the confirmation roll does not count as one of them.
The character has already 'hit' the target so he can't miss.
PHB pg 152 "If the attacker hits, the defender must make a miss chance percentage roll to avoid being struck."
Now this is how I read the action happening here.
The attacker rolls to hit the target. For arguments sake let's say he needed an 18 with a weapon that has a 20 critical range. He rolls a 20. Automatic hit and potential critical.
The target has concealment and a 20% miss chance. So now the defender rolls to see if he missed due to concealment. He rolls a 15% - he misses and can't make a confirmation roll on his critical. He rolls a 50%, he has made a successful hit and can continue with a confirmation of critical hit roll.
The confirmation of critical hit roll is made using all of the modifiers to the attack just made. If the attacker rolls an 18 or higher he has confirmed his critical hit and now rolls for the extra damage.
The assumptions here are:
That a confirmation roll is made after a successful hit is made.
A miss chance roll is made after a (normally) successful hit to determine if the hit missed.
So a character can still miss his opponent with a natural 20 roll and if he missed he can't make a confirmation roll for a critical hit.
At least that's how I read it.
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