Nielsen Admits to ‘Technical Error’ in Ratings Measurement

NEW YORK: Nielsen says it has discovered a "technical error" that impacted its measurement of U.S. broadcast network ratings since the beginning of March.

In a statement, Nielsen said that "recent ratings irregularities" prompted an internal investigation of its own systems. A "technical error" was discovered on October 6. The company said the error was introduced on March 2 and was "generally imperceptible" until the fall season premiere week, when it saw particularly high viewing levels.

"As a result, small amounts of viewing for some national broadcast networks and syndicators were misattributed," Nielsen said. Cable networks and local TV ratings were not affected.

A software fix has been implemented so that all data going forward is correct, the company stated. Nielsen will also reprocess data beginning from August 18, and is "conducting an impact analysis to determine whether additional weeks should be reprocessed. We will work closely with our clients and the industry to provide updates as soon as possible."

The problem was attributed to “all other tuning with code” (AOT with code) content, which Nielsen says represents a tiny fraction of viewing minutes credited nationally. "In the vast majority of cases, the impact is small; in a handful of cases, the impact is more significant."