Build a custom report to see how many Sessions included your top pages, and the result is confusing! Chances are you will see the number of Sessions drops sharply once you get below your primary landing pages. What gives? How can the number of Sessions be lower than the number of Users? Doesn’t every user have at least 1 session?
Blame it on Google. They made it really easy for you to build the report and didn’t warn you. The problem is that the Sessions metrics should not be used with Hit-level dimensions like Page, but Google doesn’t tell you that. They also don’t tell you what a Hit-level dimension is, and there is no simple way to figure it out. The standard reports are fine, but that Second Dimension button can be dangerous!
Why? Why? Why?
Here’s the reason: Google tags the Session count only to the first page viewed in a session — i.e. the Landing Page. Lets look in detail at a single session and how Google records various metrics page-by-page through it.
The image contains two sections – at the top, an extract of the detailed page-level metrics from the API (displayed in an Excel worksheet); and at the bottom, a copy of the Google Analytics All Pages report for the same session [click the image to see a larger version].
You can see that while there were 13 page views in total, only 7 different pages were seen (unique page views). A Pageview is counted for each page, an Entrance is recorded for the first page and an Exit was recorded for the last page. Unique Pageviews are counted only for the first visit to each unique page. Nothing unexpected there. The totals all match the standard report.
BIG SURPRISE: the Sessions are counted ONLY for the first page!
This is why you shouldn’t use Sessions when you report at the Page-level. Why would Google do this? You might think: well, there is only one session here and they count the session only once, and that is so that when you total all the metrics in the report, the total should be 1. They assign the Session count to the first page in the session, and that sort of makes sense.
A good rationale, and that might have been true once upon a time, but if that is the way things are, then why are the Users shown as 1 for every page view? That would total to 13 Users. Inconsistencies like this breed confusion for new and casual users.
You might notice that New Users also gets counted only for the first page viewed, and you might wonder if Sessions is the same as New Users, but it isn’t — the example I used just happen to be for a new user to the site. In fact, the Sessions metric reflects the Entrances for the page [there are a few cases where these will differ slightly, but let’s not get into that now].
How to Report Sessions for a Page?
If you want to see how many sessions included each page, then you need to look at the Unique Pageviews metric on the All Pages report. As we showed above, this metric is counted only once for each page in a session, so it really reflects the number of sessions in which the page was viewed. I suggest you change the metric title before you send the numbers to someone else or you will have to explain everything…
Bottom line: Do NOT use Sessions in a report with Pages! Use Unique Pageviews instead.