I asked before but nobody mentioned anything, but how exactly does an AI work. I'm guessing its like a score out of 100, right?
Don't worry, it used to confuse me as well!
I think, and I may be a bit off, that certain people within the UK are asked to vote by the ratings company and give the episode a score out of ten. An average is made from all the votes, say for example 8.7, and then it is multiplied by ten to give a score out of 100, in this example 87/100. I think if you get over 85 it's 'excellent'.
It's something like that anyway. Doctor Who usually scores in the 80's for NuWho but it's gone over and under at times, too.