The answer for Mr Cohen

In Friday’s NBR there was a half page feature by David Cohen about online readership, prompted by this blog entry.

It’s not online, so I can’t link to it, but at the end the author posed the question about why Trade Me was only listed at No 2 in the Alexa ratings when they are commonly reported to make up half the NZ traffic to websites. David actually suggested I should answer this query online, so here goes:

The answer is they measure two different things.

Alexa measures websites visited by New Zealanders. Neilsen Net Ratings measures websites hosted in NZ.

So the Alexa data includes global websites such as Google and the BBC. They are reporting their data based on whether the person visiting is from NZ.

The Neilsen Net ratings measure traffic to NZ hosted sites. This data will include visits from overseas. They are looking at whether the site is a NZ site.

So Trade Me gets the most visits of any local NZ site, and is No 2 in the list of all sites visited by NZers.

I should make a cautionary note that all data is somewhat suspect. There is no canonical ranking. TTLB uses Site Meter to measures blogs relative visits, Google Analytics measures many sites, Alexa measures those who use their toolbar etc. All had their pros and cons. All can suffer from under and over counting.

It is possible that most of the visitors from parliament to this site only count as one visit because they share the same IP address for their proxy. So they get undercounted. But on the other hand someone on a dialup account who visits multiple times per day gets double counted if they have a different IP address each time.

That’s why trends are more important than individual ratings in my opinion.