Nielsen says software glitch caused months of inaccurate data

Nielsen's television ratings for most of 2014 have been incorrect, it has been revealed, due to a software glitch that skewed some of its numbers. The news was revealed today by Nielsen itself, which said that an internal investigation was kicked off due to "irregularities" that came to light in recent weeks. A few days ago the source of those issues was uncovered: a so-called technical error that affected the ratings of national network television over the course of most of this year.

Says Nielsen, which fixed the software glitch yesterday, the problem started way back on March 2 of this year, remaining unknown until the company noticed high viewing levels when the television fall season kicked off. Neither local or cable networks were affected by the glitch; rather, certain national networks were affected.

Starting today, the data coming from Nielsen is once again correct, and on October 17 the data released since September 22 will be re-released with correct numbers. Following this, the data released since August 18 of this year — the start of the new television season — will be corrected and released on October 31.

The total impact of this software glitch will be determined in an analysis Nielsen plans to perform, and if necessary it will reprocess data for other weeks, as well, with correct numbers. Nielsen says that overall, most of the impact from this glitch is small, but that there are a handful of instances where the result was "more significant".