• by Gavin O'Malley  @mp_gavin, May 23, 2007

Measurement firms comScore and Nielsen//NetRatings have committed to timetables for the auditing of their technologies and processes by a third-party auditor. That was the main development to come out of an industry meeting convened by the Interactive Advertising Bureau last week.

Nielsen//NetRatings has formally announced its entrance into a full audit and accreditation process with the Media Rating Council, and comScore is in the final stages of its pre-audit with the MRC and has indicated a commitment to finalizing the timeline for a full audit and accreditation within the next 90 days.

The Interactive Advertising Bureau, which issued an official statement yesterday, agreed to work on updating standards for audience measurement and on marketplace education around the multiple ways that Web traffic can be measured and audience composition and behavior can be assessed.

Last Wednesday's meet-up with representatives from the major associations representing advertising constituencies resulted from an open letter sent by the IAB last month to comScore and Nielsen//NetRatings asking both firms to consider external audits.

Differences in audience measurements between the ratings services and interactive media companies had inspired the meeting, which was attended by a number of industry organizations including the American Association of Advertising Agencies, the Association of National Advertisers, the Advertising Research Foundation, the Online Publishers Association, and the MRC.

ComScore and Nielsen//NetRatings use sample-based projections to estimate total audience size and composition. Media companies use a census-based approach that relies on server logs. The IAB had asked the companies to help reveal the sources of the discrepancies by undertaking a third-party audit.

During the meeting, the IAB did acknowledge that there is a role for both panel-based and server-based metrics in the measurement of audience, and both will continue to be used by agencies and advertisers as a combined decision-making tool.

In addition, the meeting's participants agreed that "convergent validity"--which combines different data sources to provide a deeper understanding of the total audience--is important to securing increased growth for interactive advertising.