NetRatings says it has filed patent infringement suits against Web analytics firms Coremetrics and Omniture, reports ClickZ. The suits allege that both firms have infringed on four patents relating to the collection, analysis and reporting of computer usage data. NetRatings offerings include online audience and ad measurement, a media planning tool, and a reach and frequency tool.

In the suit filed in U.S. District Court in Delaware, NetRatings says it holds or controls six patents covering work in the area, including No. 5,675,510, which relates to a "computer use meter and analyzer," and No. 5,796,952, which covers "a method and apparatus for tracking client interaction with a network resource and creating client profiles and resource database."