comScore On the Impact of Cookie Deletion on Website Audience Measurement in Australia - White Paper

comScore released a white paper, The Impact of Cookie Deletion on Site-Server and Ad-Server Metrics in Australia: An Empirical comScore Study.The study addresses the key sources of discrepancy between server-based and panel-based data and reveals that cookie deletion can lead to large overstatements in servers' measurement of the size of online audiences. Without appropriate adjustments, […]

comScore released a white paper, The Impact of Cookie Deletion on Site-Server and Ad-Server Metrics in Australia: An Empirical comScore Study.

The study addresses the key sources of discrepancy between server-based and panel-based data and reveals that cookie deletion can lead to large overstatements in servers' measurement of the size of online audiences. Without appropriate adjustments, site-server measurement of the size of website audiences in Australia can be inflated by up to 2.7 times the actual number of unique visitors.

Here're the key findings:

  • Appx.28% Internet users in Australia delete their 1st-party cookies in a month. 3rd-party cookie %tages are even higher, with nearly 37% deleting 3rd-party cookies in a month.
  • "Serial cookie deleters" have a profound impact on inflating site-server logs because they represent a small %tage of computers, but a very large share of observed cookies.
  • Because of high rate of cookie deletion, a server-centric measurement system which uses cookies to measure the size of a site's visitor base will typically overstate the true number of unique visitors by a factor of up to 2.7x in Australia.
  • Similarly, the study found that an ad-server system which uses cookies to track the reach and frequency of an online campaign will overstate reach by a factor of up to 5.7x and understate frequency to the same degree.
  • Comparing cookie deletion in Australia with other markets across the globe including the U.S., U.K., Brazil, France, Germany and New Zealand found that each country saw 3rd-party cookies being deleted by appx. 30-40% users, with 1st-party cookies deletion in excess of 20% in each country. Australia fell in the middle of the distribution among the included markets for both 1st-party and 3rd-party cookie deletion percentages.

Reference: Study

[tags]cookie,web server,australia,site server,ad server[/tags]

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