An average of 2.5 cookies were found per home computer in a US Survey [hat tip attentionmax] by Comscore. It seems that 31% of people delete their cookies at least once during the month*, and 7% delete them 4 times or more.
Let’s see how that works in NZ.
NetRatings shows there were 6.1m domestic unique browsers in March. There are only 4.1m of us here, so clearly that is too high.
6.1m domestic browsers/ 2.5 cookies per browser = 2.45m computers that accessed the internet in March, assuming that work and home computers have the same cookie deletion rates.
That’s computers. We should remove cases where people have more than one computer. Actually we should just count the number of cookies per person.**
We should increase the number for situations where multiple people use one computer (flats and some places of work) and reduce the number for people with both a work and home computer.
Overall this does not really matter as long as the industry is settled on how many people total are online, and how the pageviews and UB’s divide amongst the sites. The industry, aside from holdout YahooXtra, is settled on these things.
*By the way – I’m guessing that a significant reason for the deletions is computers crashing.
**I did this at Trade Me a few months back. Can’t state the results sorry. But Net Neilsen shows 3.6m total traffic UB’s for March for Trade Me. Trade Me shows 1.6m active members, who are not necessarily active each month.