Analytics Tuesday – Cookies

Last Tuesday, in the first in this series of posts, I looked at some of the main reasons for gathering metrics from your site. This week, I want to start covering some of the key terms you’ll come across in discussions of metrics.

I’m going to start with ‘cookies’.

No, not those sorts of cookies.

Cookies are probably not the first thing you think of when you think about capturing metrics from your site. You may not think about cookies at all, in fact. However, they’re pretty damned important. Here’s why.

Cookies and Page Tags

For the sake of simplicity, I’m going to assume (dangerous, I know) that you’ve plumped for using Google Analytics (GA) as your metrics package of choice. After all, it’s free and the range of data it supplies is probably enough for the great majority of small businesses. Best of all, it uses page tags that you add to each of your site’s pages – so you don’t need access to your server logs – and the data is available to you through your own on-line dashboard at Google.

Page tags work (i.e. gather data) by setting cookies when visitors arrive at your site. Cookies have had a bad press, which, for the most part, is a result of ignorance. After all, a cookie is simply a very small text file (which can always be examined by a user in a normal text editor, or even deleted) that gets associated with your browser when you visit a site.

Then, whenever your browser accesses that site, it takes the cookie with it. It’s a way for a site to recognise repeat visitors or visitors accessing more than one page in the site.

If you use Amazon, for instance, you know that when you use your normal computer, you’ll get the ‘Welcome, Graham’ message (replace ‘Graham’ with your own name!) but when you visit from a different computer, Amazon doesn’t know who you are. That’s the power of cookies.

GA uses only first party anonymous cookies. This is what Google says about its cookies in its help area:

Google Analytics uses cookies to define user sessions, as well as to provide a number of key features in the Google Analytics reports. Google Analytics sets or updates cookies only to collect data required for the reports. Additionally, Google Analytics uses only first-party cookies. This means that all cookies set by Google Analytics for your domain send data only to the servers for your domain. This effectively makes Google Analytics cookies the personal property of your website domain, and the data cannot be altered or retrieved by any service on another domain.

The down side, of course, is that some companies and people prevent cookies being written to their computers. That means you’ll miss some of the data you want to collect. The number will be small, however.

Next week, I’ll look at one of the key areas where cookies come into their own: differentiating between visits and unique visits.

Remember, if you miss one of the Analytics Tuesday posts, you can simply click on the blog topic in the sidebar with that name and you’ll see a list of the posts so far.