I think it's "impaired". Taking the example of the visually impaired, where their sight is not very good, it probably means a proof with some minor problems....
Me too Sylvester! My favourite is the Jubilee head then the Gothic. My fave effigy though is George IV because it seems so animated and ugh I can't describe it - it's wonderful!
That's one of the best ideas I've heard. Setting it to calculate the mean would also save you a helluva lot of work. Plus if you could set it to log the highest and lowest that would be interesting for us but you couldn't put it in the book.