Nielsen, the company that provides data about what people watch, listen to, and purchase, is calling for a new set of rating standards due to the growing popularity of accessing media content via tablets and other devices. This statement came after Viacom’s recent criticism of Nielsen, claiming that the research firm is outdated because the ratings do not consider digital viewing methods. Nielsen admits that its ratings for broadcast networks have been inaccurate for seven months now.

Viacom’s networks experienced a tumble in ratings in the third quarter, which reportedly led to a decline in ad sales.

In MediaPost, Nielsen highlighted its recent efforts to make smartphone and tablet viewing eligible for inclusion in the ratings calculation, but it pointed out that the ratings used to reflect the average audience of commercials is flawed.

An industry-defined standard only allows ads that are not changed for different audiences to be eligible for the ratings. However, the popularity of dynamic, targeted ads has made this standard almost irrelevant.

Nielsen recommends that the industry adopt new standards which combine the total audience for a program including streaming video-on-demand.

Viacom’s chief executive Philippe Dauman criticized Nielsen for its slow action to change the ratings system. According to The New York Times, “Ratings for Viacom’s networks, which include MTV, Comedy Central and Nickelodeon, tumbled 15 percent during the quarter that ended in September.”

Domestic ad sales fell 5 percent in the same period, so Dauman plans to make 5 percent of its domestic ad sales independent of Nielsen ratings. Currently, about 30 percent of Viacom’s domestic advertising revenue is from ad sales for mobile apps, personalized advertising, and sponsorships, all of which are independent of Nielsen ratings.