When we talk about ‘visitor numbers’ at grapevinejobs, we refer to 'unique visitors'. This is different from ‘visits’ [one person visiting the site 20 times in a month counts as 20 visits, but only one unique visitor].

Confusingly, there are different ways of counting unique visitors. We use Google Analytics software to gather our visitor data. This is a well-respected package which produces results almost immediately. However, while it’s fast, it is not thorough – and to get truly accurate results, the data must be manually audited which is time-consuming and expensive.

In January-09, we had our visitor data manually audited by the independent organisation ABCe [www.abce.org.uk]

The ABCe audit certificate shows actual unique visitors of 40,189 (view) – which is 22.63% MORE than the Google Analytics number of 32,773 (view).

The main explanation for the difference is that Google doesn’t take into account situations where multiple users connect through a single IP address (which is the case in many companies).

We don’t intend to repeat the ABCe audit very often, as each one takes weeks and costs more than £5,000. Meantime, we continue to use Google Analytics data, while remaining quietly confident that it materially understates our true visitor numbers.