User Agent strings and Web analytics

In every Android browser I've used, I've changed the user agent to represent itself as Desktop in order to avoid the mobile ghetto many popular websites think mobile users deserve. They lack the links and features of the full fledged pages, and while there may have been a great reason to have a mobile site during the Treo days, it's simply a nuisance on today's Android phones.

I always go as Desktop on all of my Android devices. But iOS Safari users have no such option. When you surf the Web on iOS, you're using Safari identified as mobile.

I wonder for all of these reports that iOS accounts for the lion's share of "mobile" Web traffic, do these stats identify mobile users by their user agent strings? And if many Android users surf the net as Desktop and not mobile, how much does that skew the statistics?