Nielsen/NetRatings will scrap rankings based on the longtime industry yardstick of page views and begin tracking how long visitors spend at the sites, an Associated Press report said.
The move comes as online video and new technologies increasingly make page views less meaningful, the Associated Press report said.
The report said although Nielsen already measures average time spent and average number of sessions per visitor for each site, it will start reporting total time spent and sessions for all visitors to give advertisers, investors and analysts a broader picture of what sites are most popular.
Currently, sites and advertisers often use page views, a figure that reflects the number of web pages a visitor pulls from a site, the report said.
However, Yahoo and others are increasingly using a software trick called Ajax to improve the user experience, the report said.
It allows sites to update data automatically and continually, without users needing to pull up new pages. Page views decline as a result, the report added.
Page views also drop as people spend more time watching online video at sites like Google's YouTube, the report said.