Thanks for your comments. #1 Android tablets are an interesting one. Do we think people are more active in terms of Google searches on Android tablets than on Android phones or desktop? I'd suggest they're less active (in searching terms) than on desktop. Than mobile - well, the received wisdom is that Android tablets are largely used for consuming video, particularly in Asia, which is where a lot of them are. It's an oversight on my part, I agree, but I'm not sure they make a big difference.

#2 Gartner revised its calculation for the PC base earlier this year - if you followed my linkblog you'd have seen the reference to its latest calculation [1] which puts the number at 1.48bn in 2015, falling constantly towards 1.38bn in 2019. That might get revised, of course, but the 2015 figure is probably accurate.