- February 11, 2009

Cookies Still Food for Thought for Online Advertisers in Europe

At the WARC “Measuring Advertising Performance” conference at the Royal Garden Hotel here in London last week, Comscore’s SVP and Managing Director of Europe, Mike Read, presented a very digestible overview of the current tools available to advertisers and agency planners in the online arena.

Mike covered a range of topics including the segmentation of heavy, medium and light Internet users, behavioral and socio-demographic targeting, and how to maximize return on investment when planning online media campaigns.

One significant take-away from the question and answer session that followed, was how concerned the industry still is with the issue of cookie deletion, and the overstatement of site visitors that site-centric (i.e. server-side) data can cause.

Frank Harrison, Strategic Resources Director at Zenith Optimedia Worldwide, flagged the overstatement of unique visitors based on site-centric data as one of the key challenges facing the industry.

“The cookie deletion issue is big and growing and there is a real need for transparency and clarity regarding it,” said Harrison. “If cookie deletion does indeed mean that reach is overstated by up to 2.5 times, there is an equivalent understatement of online ad frequency, and that needs to be addressed. Advertisers need to know what they are getting for their money online.”

Using cookies as a viable metric to count online eyeballs has been a hotly contested issue for some time in the U.S. and, increasingly, it is being acknowledged by media buyers and sellers alike that cookie deletion inflates server-side estimates of the true number of unique visitors. In fact, a recent legal episode in the U.S. has vividly demonstrated the magnitude of the issue: http://www.mediapost.com/publications/?fa=Articles.showArticle&art_aid=99911

The feedback of Mr. Harrison and others in the U.K. indicates that the debate on this side of the pond has gone from simmer to boil, provoking new concerns in the agency world about the inherent inaccuracies in the use of cookie-based methodologies as a valid way to measure online advertising reach and frequency.

Comscore authored an empirical research study on cookie deletion nearly two years ago that has gone a long way towards resolving debate in the U.S. about the impact of cookie deletion on server-side measurement and which demonstrated that panels (which don’t rely on cookie-based counting) are a much more accurate approach. Perhaps it is time that Europe gain a deeper understanding of the issue as well.

If you are interested in learning more about the effects of cookie deletion, please download your free copy of the Comscore Cookie Deletion White Paper: http://www.comscore.com/request/cookie_deletion.asp