Nielsen, the company that calculates the ratings networks and advertisers use to set advertising rates for television shows, found a mistake in its calculations Monday that calls into question all of the numbers it has reported since March. This error is a big one for Nielsen because the Nielsen ratings essentially determine the fate of television shows: they affect which shows get renewed and how much ads sell for. It's potentially a huge credibility blow to the company at a time when its statistical sampling-based method seems increasingly outdated in light of modern technology.
"The technical error was introduced on March 2, 2014, and was generally imperceptible until we saw high viewing levels associated with fall season premiere week," a statement from Nielsen reads. Thus, it's unlikely that the shifts in the ratings will be major. What's important is that this kind of mistake calls into question Nielsen's methods.
The big issue here is that Nielsen is constantly battling off arguments that it should be replaced by something that literally measures what everybody watches, which would be easy enough to do with the vast proliferation of digital viewing options, from online streaming to cable boxes. Nielsen does not count every viewer watching a show. Instead it constructs a representative statistical sample of the US population, then calculates viewership rates based on what that sample watches.
"Nielsen is committed to upholding the highest standards of television audience measurement and data processing," the statement reads. Nielsen will remain the standard for television ratings for the foreseeable future, as no one can yet agree on a viable alternative. But this is a hit to its credibility that it will have to rectify in the months to come. It's already in the process of doing so — all ratings data since March is being recalculated.