Hats off to the NetRatings team in London for some really savvy insights into how to crunch audience data. These graphs show new ways to measure the elusive form of 'engagement' based on a blend of the time spent with a site, the number of pages viewed and the involvement of the viewer. As the online industry struggles for smarter ways to think through these issues, this is a real leap forward in understanding.

Web Analytics Academy | Some of the challenges in web measurement for publishers and marketers