• by Mark Walsh  @markfwal, March 25, 2013

comScore on Monday officially launched its new cross-platform reporting system combining audience metrics from Web sites, video and apps across PCs, smartphones and tablets.

Unveiled in beta in November (with September data), the company's Media Metrix Multi-Platform reporting aims to provide a more complete view of an online property’s audience as people increasingly access the Web and other content on mobile devices.

The impact of the mobile shift has been especially pronounced for a handful of top 100 sites, especially where combined desktop and mobile U.S. audience in February increased by triple digits, according to the new comScore numbers. That includes mobile-centric properties like Groupon, up 223%, Zynga (211%) and Pandora (183%).

Across the top 100, the unduplicated audience grew by an average of 38%, with 19 properties seeing the reach of their desktop audience expanded by 50% on smartphones and tablets. (comScore mobile figures reflect use on the iOS and Android platforms.)

Among sites in the top 25 that saw a healthy ratings bump from the combined desktop/mobile reporting were Apple and Twitter, both up 54%, Yelp (51%), the Weather Channel (37%), eBay and About.com (both 29%), Gannett sites (32%), and Amazon (27%).

With the exception of properties like Pandora, the ranking of the top sites remained similar to that when counting desktop-only traffic. The top five multiplatform sites in February -- Google, Yahoo, Microsoft, Facebook, and Amazon -- were the same ones as through the standard Media Metrix ratings in January.

comScore said the cross-platform reporting will give publishers and media companies better insight into the nature of their audiences in order to align content and marketing strategies and monetization efforts. For media planners, it can help to optimize audience reach and frequency within and across channels.

Public companies like Pandora, Zynga, Yelp and Facebook have already begun highlighting mobile audience metrics in quarterly reports in relation to steps they are taking to monetize the sharp rise in mobile usage. Pandora, for example, reported earlier this month that mobile revenue in its fiscal fourth quarter surged 111% -- even faster than the 70% increase in mobile listening hours.

For now, comScore will continue to publicly release the desktop-only Media Metrix top 50 Web properties on a monthly basis, but will regularly publish the Multi-Platform ratings in some capacity alongside, according to Andrew Lipsman, vice president, industry analysis at the digital measurement firm. He added that other services, like the Video Metrix and Mobile Metrix ratings, will be maintained. 

The new cross-platform tracking service overall includes reporting on more than 300,000 digital media entities, including their unduplicated audience size, demographic makeup, engagement, performance within key user segments, and behavioral trends.