Zero visits
Google Analytics contains a Keywords report inside the Traffic Sources section. This lists the phrases (or "keywords") people used in search engines to find the site. This report shows how many visits each phrase generated. If you have a site with thousands of keywords, and you drill to the bottom of the list, you will find phrases that generated zero visits. Given that a phrase only gets recorded when someone visits the site, it didn't seem possible to me to see zero visits.
I logged a question with Google Analytics support and got this reply:
"I reviewed the keyword report in your Analytics account and was able to confirm that some keywords have zero visits. Please be assured that this is normal and usually happens when a visitor may click on your advertisement or search listing, but prevents the page from fully loading by navigating to another page or by pressing their browser's Stop button. In this case, the Analytics tracking code is unable to execute and send tracking data to the Google servers. However, keyword information may get captured."
Readers with even a hint of technical knowledge will recognize that this answer is complete rubbish. This is obviously the work of a support technician who has no idea and is simply making it up. It is not the execution of the tracking code that generates the instance of a visit. The Google Analytics system records a visit when it gets the data from the tracking code. It is therefore not possible to record any data and then say no visit occurred. If you record data, you have a visit. The lesson here is not to trust responses from Google support blindly. I explained to my new Google friend why I didn't accept their answer, and they kindly escalated it to their technical team.
Eventually, I got the following response:
"If a user searches for keyword 'A', clicks on the link to your site, then goes back and searches for keyword 'B' and also clicks the link to your site, the visit is only attributed to one of the keywords. The other keyword receives zero visits. This may explain why a few of your keywords have zero visits."
Technically, this is vaguely legitimate under the standard. If you leave a site, but return within 30 minutes, it is still the same visit. For example, if I spend 10 seconds on your site, go off to a different one for 20 minutes, then come back to yours for another 10 seconds, then go somewhere else for 25 minutes, then come back to yours for 10 seconds, this is all one visit on your site, with a total duration of around 45.5 minutes, even though I only spent a total of 30 seconds on your site.
A visit does not end when you leave a site. A visit ends when more than 30 minutes has elapsed since you last opened a page on that site.
A session ends when you leave the site. While the example above is one visit, it is three sessions. However, people mix visits and sessions together and treat them as the same thing.
I am not sure what this does to the stats for a site. This will almost certainly cause discrepancies between Google Analytics and traffic reports for Google Adwords. I suspect it will affect other reports as well, but I'm not sure how.
Conclusions
While Google Analytics is a good system, it lacks documentation. Google portrayed the system as suitable for large sites and professional analysis, as well as mom-and-pop shops. They have some large site case studies to back it up. In general, I'm inclined to agree. However, serious analysis requires an understanding of how data is processed, what standards are supported and how. Google needs to be clear in its communication. Switching the way Average Time on Site was calculated was a big deal and should have been announced on the interface, not left for support to handle.
Meanwhile, the example we've seen here of a Google support technician just making answers up without any real knowledge indicates a dire lack of training in web analytics.
Google Analytics is a sophisticated product. Let's hope Google's documentation and support can grow to the same level.
Brandt Dainow is an independent web analytics consultant and the CEO of ThinkMetrics. Read full bio.