The Appreciation Index or AI is a measure of how much the audience enjoyed the programme. The score, out of a hundred, is compiled by a specially selected panel of around 5,000 people who go online and rate and comment on programmes.
The AI of 82 is fairly low for Doctor Who, but is in the 'good' category. It's very slightly down from The Time of the Doctor's 83, and matches several Series 8 episodes - an updated leaderboard is below:
- Mummy on the Orient Express, Flatline & Dark Water - 85
- Into the Dalek & Time Heist - 84
- The Caretaker, In the Forest of the Night & Death in Heaven - 83
- Deep Breath, Robot of Sherwood, Listen, Kill the Moon & Last Christmas - 82
[Source: Doctor Who News]