NEW YORK: Top US advertisers including Procter & Gamble, AT&T and Unilever have added their weight to the mounting clamour for a re-think over TV ratings measurement.

Frustrated by the lack of progress at Nielsen – whose grasp of audience data is being weakened by the growing plethora of digital platforms – the three big hitters have joined forces with networks owned by Time Warner, News Corp and Walt Disney, as well as GroupM, the media umbrella of WPP, to force the pace of change.

A new consortium, which supporters say will award its own contracts for measuring set-top box data and cross-platform viewers across TV and digital sources, is likely to be operational as early as next month.

The viewing data gleaned by ratings giant Nielsen, which controls the measurement of US audiences through remote control devices in 18,000 homes, has for decades served as the benchmark for the $70 billion (€49bn; £42bn) US TV advertising market.

But despite the firm's dominance in TV audience measurement, there has been growing unrest among media companies and marketers over Nielsen's apparent sluggishness in reacting to changes in viewing habits.

The firm, whose second quarter results earlier this month revealed a decrease of 6%, took more than a decade to switch from written diaries to electronic meters.

In recent years, the fragmentation of TV and its migration to new platforms such as iPods and mobile phones has become even more of a challenge for the firm.

The involvement of the mighty P&G and AT&T, ranked as the largest and third-largest advertisers in the US respectivley, highlights just how urgently blue-chip names feel the need for more accurate information for ads running across multiple platforms.

"The most deficient thing is there's no single source measurement [for TV and digital video]," Sam Armando, senior vice-president of audience analysis at Starcom Mediavest, told the Financial Times.

Data sourced from Financial Times; additional content by WARC staff