Online Metrics Done Wrong Part 2 — Tracking IP Addresses

Posted by: Pete Horadan

Last week, we looked at the serious acurracy issues associated with using cookies to track visitor behavior and engagement. This week we’ll explore the accuracy of another often-used factor, IP address. In short, IP address provides even less information about users than a cookie.

The accuracy issue starts with the fact that one user may have many IP addresses. For an example, let’s look at me. I access different sites (e.g., TechCrunch) from home through my personal broadband, while at my coffeehouse through their broadband, or through the network at my corporate office. When I’m on the road, I broaden my access points to include hotels and airports. When using IP address to count visitors, the information collected for me might look something like this:

IP Address Domain Location
24.16.13.198 comcast.net Woodinville, WA
208.54.4.23 tmobile.net Issaquah, WA
70.103.221.189 scoutanalytics.com Issaquah, WA
12.204.178.67 marriott.com New York, NY

Of course this is incorrect. What appears to be four unique visitors, is really only me.

The flip side is true as well, namely one IP address may have many visitors. The common example is found when visitors behind an office firewall may all appear to come from the same address. In this case, paid-content providers have no visibility into individual visitors or their different behaviors. So, when trying to analyze unique visitor counts from IP addresses, the problem is almost intractable. Does a given IP address represent one visitor, many visitors, or just a fraction of a visitor?

On their own, IP addresses have serious limitations in terms of establishing unique visitors or tracking behavior, seriously over- or under-estimating the true picture. Improperly used, they can lead to faulty analysis. IP addresses are best used to provide hints which I’ll discuss more in future posts.