Nielsen’s numbers in early November reported a sharp decrease in Nickelodeon’s viewing figures, down 9% in September and 15% in October, according to a Morgan Stanley analyst. As a result, the channel was forced to give advertisers free airtime to compensate for the shortfall in audience.

A Nielsen spokesperson told Research today: “We have worked closely with Viacom and the Media Rating Council to conduct an exhaustive assessment of the methodological and market factors reflected in national TV ratings. To date, the review process confirms that our measurement methodology, operations and related reporting processes are working as expected.”

Earlier this week Viacom CEO Philippe Dauman (pictured) told the UBS Media & Entertainment conference in New York that “however imperfect Nielsen is, it’s the only game in town” and that the company would “have to live with it”.

Meanwhile, Nielsen has confessed to one error in its data. Figures provided to the Wall Street Journal in late November showed a 1.7% increase in TV viewership among children aged 2 to 11 for the current season. Nielsen has since said that it did not apply a standard adjustment for year-over-year comparisons and that the correct figures actually showed a 2.9% decline in children’s viewing compared to 2010.