Causes of Cookie deletion

[sirpatrickspens]

Anybody know of a good list or report that estimates the impact of the different causes of cookie deletion?

Am trying to help my company understand their reach metrics more accurately and would like to drill into the impact of cookie deletion on our unique user numbers. Have been reading the Jupiter and Comscore reports but they don't really go into the causes, just the impacts on overcounting

Any leads appreciated!
Patrick

[bradbox]

This is an interesting, although slightly technical description of why Unique Visitors appears so differently across different technologies:

http://groups.google.com/group/analytics-help-tracking/browse_thread/thread/6d1f20f47e38e3e6?fwc=1

To answer your question though, about cookie deletion, I would expect it is very, very low. Most users just don't know how to delete cookies, or disable them, and more and more sites nowadays are a right pain in the backside to use if you keep deleting cookies - so it inhibits the user experience.

In Omniture and Google Analytics we tend to use Visits rather than Uniques, because if I browse a site at work and home, I'm classed as 2 Uniques, which is incorrect anyway.

Commercially, i.e. to value our visitors, we simply value Page Impressions for sponsorship and ad revenues (CPM), or registered users - which are absolute uniques.