IT Pro versus Google: whose site traffic figures do you trust?

I’ve been looking at Google’s new Ad Planner tool. As Google says, it is “a free media planning tool that can help you identify websites your audience is likely to visit so you can make better-informed advertising decisions.”

They could also add that PR firms may want to look at it in terms of building an online media target list.

As ever with Google, the Ad Planner tool reveals a host of interesting data based around demographics and interests as well as access to aggregated statistics on the number of unique visitors, page views, and other data for millions of websites from over 40 countries.

However, one part of the tool that intrigued me was the ability to see detailed info on an individual site’s visitors and page views. For example, take a look at IT Pro (I’m not singling out IT Pro for any reason – just happened to be the first one I looked at). According to the publisher (Dennis), IT Pro has:

311,000 unique users

1.1 million page impressions a month

According to Google, it has:

33,000 unique UK visitors (86,000 worldwide)

120,000 page views (260,000 worldwide)

Google also provides a nice little graph showing daily visitor rates – so IT Pro seems to toggle above and below the 1,000 daily visitor rate in the UK. It also tells you where else visitors to the IT Pro site go – mainly in the Dennis fold it would seem – and

The big question here is: whose figures do you use? Both as a potential advertiser or planning a PR campaign, you’d want to be sure that you were basing your decisions on accurate data. (And Chris Green’s plan to reward freelance journalists on the basis of traffic figures clearly hinges upon this).

So what is the explanation for the wide variance between what the publisher says and what Google says? I don’t know (and I haven’t had time to do an exhaustive analysis to check if this is just a one off or there are universal differences between publisher data and Google’s data).

If anyone has any thoughts on the matter, I’m all ears. At the end of the day, I’m sure the only thing people want is accurate information.