• by Mark Walsh  @markfwal, April 21, 2011

With publishers extending their presence across a growing array of devices, comScore Thursday rolled out a new audience measurement service reporting total traffic across mobile phones, apps, tablets, and shared computers, as well as on the traditional Web.

The comScore Media Metrix Total Universe report will be available to clients with the release of April data in the U.S. and U.K., with other markets to follow.

Publishers are required to add a Unified Digital Measurement tag to participate in the report, which will feature standard metrics such as unique visitors, reach, and page views across multiple media platforms. A comScore spokesperson said about 90% of the top 100 Web publishers are currently using the UDM tag.

"With digital media fragmentation occurring at an accelerating pace, it has never been more important for publishers to understand the full size and composition of their audiences and get credit for the traffic they're generating across all media platforms," said Cameron Meierhoefer, comScore executive vice president of analytics. He added that the comprehensive new tracking would help publishers monetize their content regardless of the access point.

A lack of standardized audience measurement has long been viewed as a barrier to increased ad spending in mobile. To the extent that comScore's cross-platform reporting can give both publishers and marketers a better picture of a site's entire audience, as well as by device category, it could help bring mobile advertising more into the mainstream.

"Consumers have so many different ways of accessing digital content today, and it's important to have a full understanding of these audiences in the increasingly fragmented environment," said Stuart Schneiderman, senior director, corporate digital research at MTV. "We look forward to evaluating comScore Total Universe as we further build our understanding of how our audiences consume content across screens."

Heidi Browning, senior vice president, strategic solutions at Pandora, noted that many users often access the Internet radio service through phones, tablets and other connected devices rather than the PC-based Web. Providing third-party measurement across these newer segments would boost digital advertising and content innovation, she said.

Earlier this week, comScore released data showing the difference that wider audience tracking can make in comparing the reach of the Android mobile operating system with Apple's iOS. Just looking at smartphones, Android is well ahead, with 33% share of U.S. subscribers versus 25% for iOS. But when tablets and other media devices like the iPod are added in, iOS has a 16% share of mobile users compared to Android's 10% -- a point Apple noted during its earnings conference call yesterday.

Unlike its monthly Media Metrix report ranking the top 50 online properties, comScore does not initially plan to publicly release the Total Universe rankings. That may change over time.