Criticals - do they get diminishing returns like normal damage after attribute 12?

I.e. normal weapon hit damage gets less of an increase per attribute point above 12. Does critical damage follow this rule too, or does it increase to 16 in a linear fashion? The otherwise excellent combat mechanics guide on this site is unclear on this.

Also, is there at least an approximate formula for crit probability?

Not sure on Critical procedures< I hate math> but here's my shot:

I tend, as a warrior primary, with 12, to get nearly as many criticals as a 16 <sup+hat or whatnot>, because most of the time now, when firestorm is cast, they run <AKA flee, and while your back is facing the opponent, every hit is critical. But say no firestorm; with 12 in axe/sword/hammer <whenever I switch back and forth> I tend to not score "any more" crits then I would with 12. I just tend to hit closer to max damage everytime. Thats about it.

--The Shim