Nielsen says its Web traffic data is flawed

SEATTLE — The Nielsen Co. says a technical glitch caused it to underestimate the amount of time people in the U.S. spent online.

Nielsen is one of the top sources of Web traffic data that many companies depend on.

A problem its system is having problems recognizing long website addresses, or URLs, has led Nielsen to report people spent about 22 percent less time on certain websites compared with a year ago.

Other problems helped push down its estimates, but Nielsen did not say what those problems are.

The company is looking for similar errors in Web audience reports it issued in other countries. Nielsen also is examining reports tracking online video consumption, Web search traffic and other areas.

Nielsen says it will correct the problems for its December report, due out in January 2011.