As the shift towards web advertising gathers momentum, big name US marketers are demanding audited ratings for their online media.

The Interactive Advertising Bureau announced last week that as from 2008 companies including BMW, Colgate-Palmolive, Ford Motor Company, HP, ING, Kimberly-Clark, Pepsi and Visa will pay for online ads only on the basis of audited and certified numbers.

Says IAB ceo Greg Stuart: "As more and more dollars migrate over to interactive, it is imperative as an industry that we continue to strive for the highest levels of transparency and validity."

The IAB has already gone some way towards its stated aims via the Global Ad Impression Measurement Guidelines which was announced in November 2004.

These offer a detailed definition for counting an online ad impression and an industry-driven third-party auditing and certification recommendation.

As a result a number of internet businesses have already completed audits and certification, including AOL, Atlas, CNET, DoubleClick, Univision, the Walt Disney Internet Group, and Yahoo.

Data sourced from (UK); additional content by WARC staff