Two companies that specialize in measuring internet audiences agreed to merge yesterday. Media Metrix Inc, based in New York, and RelevantKnowledge Inc of Atlanta, Georgia, will combine, retaining the Media Metrix name. The two claim the merger will create the largest audience measurement company and help create a standard method for reporting on audience figures for web sites. Such a standard has been called for by web site advertisers and agencies, and is seen by many as a necessary prelude to increased advertizing revenues from the web. The two companies together currently cover 15,000 web sites and proporietary online services such as America Online, as well as other interactive media such as Pointcast and Juno. Both use a panel-based approach to audience measurement, with Media Matrix tracking a sample set of users through software meters installed on their systems. The combination will increase the size of the sample to over 40,000 people, measured at home, work and school. Both firms provide monthly, weekly and real-time data reporting, and have a combined client list of 250 that includes most of the major advertising agencies, along with Microsoft, AOL, Intel , IBM, General Motors, Yahoo!, Netscape and Amazon.com. The company claims it will represent 85% of the total dollars spent on internet advertizing, marketing and e-commerce. The market for measuring web traffic is becoming increasingly competitive, and consolidation has appeared inevitable for some time. Media Metrix – previously known as PC Meter – was one of the earliest in the field. Financial terms of the deal were not revealed.