His formula would become a way of taking the market's temperature, of providing a measurement.

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Beyond that, it almost goes without saying that this news is extremely exciting for marketers, as it legitimizes the argument to pursue social TV initiatives with the confidence in measurement that only a Nielsen can provide, thus creating a real market for new approaches, startups and content in the TV space and allowing for new lanes of marketing innovation.

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Sales of its CDs and DVDs were down 16% compared with a year earlier, by the same measurement, which the company blamed on "weakness in the market".

BBC: HMV warns over its future as sales continue to fall

Government figures on home sales also might give a false picture of the strength of the housing market because they rely on seller-reported prices without independent measurement.

NPR: China's Struggle To Measure Economy Clouds Outlook