Segmenting Unique Visitors in Google Analytics
October 20, 2009 by Justin CutroniGoogle Analytics now has the ability to EASILY segment Unique Visitors. Some of you may be yawning, but I can hear many, many people saying, “That’s fuc*ing AWESOME!”
Unique visitors is a critical metric especially in the advertising industry. But it’s also a really hard metric to measure because it take a lot of data processing power. Why? Because of the way unique visitors are identified and measured.
Google Analytics defines a unique visitor as a cookie. For all you nerds it’s the __utma cookie.
Every time a visitor visits a site GA checks for the cookie. If the cookie exists then GA knows the visitor has been to the site before. If the cookie does not exist GA sets the cookie and increases the unique visitor count.
The challenge is that every time you want to view a report that contains unique visitors GA has to literally count all of those cookies collected to find how many are unique. That’s why there was only one GA report with Unique Visitors (Visitors > Visitor Trending >Absolute Unique Visitors report).
But Google figured out some way to effectively count all of the cookies in real time. Now the unique visitors metric that can be added to any custom report.
If you need to segment unique visitors you can simple create a custom report and include this metric.
Here’s an example. Let’s say you’re running a branding campaign for an upcoming movie. You want to measure how many actual people visit your website. You can create a custom report with the campaign dimension and the Unique Visitor metric.
There is one technical limitation. Google Analytics will sample data when a date range for the custom report contains more than 200,000 visits.
Still, I’m completely amazed that they figured out how to make this happen.
6 Responses to “Segmenting Unique Visitors in Google Analytics”
Hi, Justin!
I keep reading your blog a time ago. And Google Analytics Update is a good news.
I have a question about unique visitors. I have created a custom report with two metrics: visitors and unique visitors, and dimension month. And this report shows the number of unique visitors(141533) more than number of visitors(141077). How can that be?
By Daniil on Oct 26, 2009
Hi Daniil,
Thanks for reading the blog for a long time! As for your question, I’m guessing that you are referring to the ‘visits’ metric and not the ‘visitors’ metric? Visitors should be disabled in the custom report when using Unique Visitors.
I did a few checks and created a report with Unique Visitors and Visits. When applied to a bunch of profiles I also got more visits than Unique visitors. Which, as you point out, is the way it should work. When GA calculates the number of Unique Visitors its actually counting the number of cookies and applying some additional logic to insure that there is a unique count of people. So there is a lot of logic that goes into the calculation.
Justin
By Justin Cutroni on Oct 26, 2009