Page views, a widely used audience measure used by advertisers to decide where to spend their money, are becoming less significant amid the growing use of audio and video on the internet and websites' ability to automatically update content while people are on a site.
Nielsen is adding "total minutes" and "total sessions" information to better measure the degree to which websites engage their users.
Nielsen said the top three websites by minutes spent were AOL, Yahoo and MSN/Windows with 25, 19.6 and 10.6 minutes respectively, although at least half of these were from instant messaging and e-mail applications. Google, with the biggest unique audience, ranks fifth in terms of minutes.
"Total minutes. . . not only . . . ensures fair measurement of websites using rich internet applications and streaming media, but also of web environments that have never been well served by the page view, such as online gaming and internet applications," said Scott Ross, director of product marketing for Nielsen's NetView service.
Nielsen and rival ComScore recently agreed to independent auditing of their numbers, as their measures for page views and other metrics often differ from each other and from websites' own measurements.
The Interactive Advertising Bureau, which represents many of the biggest online publishers, is putting together guidelines with definitions for unique users, time spent and other online measures.
"People are making decisions about where to spend their advertising dollars and there needs to be transparency," said Sheryl Draizen, general manager of the IAB.