Misunderstood Metrics: Sessions for Pages

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?

sessions-for-pages

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?

sessions-for-pages-detailHere’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].

See your own website data: Misunderstood-Metrics-Sessions-Pages.xlsx and refresh with Analytics Edge Simply Free

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.

Discover Other Misunderstood Metrics:

Comments: (moderated, no spam)

  1. Laura

    I’m still confused – here’s my problem:

    I am comparing organic google traffic from Jan 1, 2017 – March 31, 2017 when compared with the same time period in 2016. With no secondary dimensions selected it says the total google/organic number of sessions in Jan 1, 2017 – March 31, 2017 is 51,343 and the total number of sessions in Jan 1 1, 2016 – March 31, 2016 is 54,191.

    I found the difference to be 2,848 sessions.

    I apply the Landing Page secondary dimension and started to add up the differences in sessions when broken out by landing page and the number is more than what the original total was. For example,

    Landing page 1 saw a difference in 1,333 sessions
    Landing page 2 saw a difference in 2,000 sessions
    and so on.

    I do not understand why the landing page differences don’t add up to the total google/organic sessions.

    Reply
    1. mike_sullivan

      This has more to do with Google’s backend than the data. When you do date comparisons, Google uses a different type of query to build the report. The base report uses a pre-aggregated series of metrics. When you add the extra dimension (Landing Page), it has to go back and recalculate the numbers from the detail data, and it looks like the process returns slightly different results. One would expect computers to always return the same numbers, but in Google Analytics this is not always the case. Google does a lot of processing to create the pre-aggregated metrics for the standard reports, and it is possible that the algorithms have diverged over time.

      Reply
  2. johnnybegood

    I’m still bewildered by some of this Google Analytics logic.

    We have a destination goal. Say, a “thank you” page once a user submits a contact. I have set up a goal for this for quite some time.

    The goal will say 29,000 people have completed the goal in November, for instance (reached the ‘thank you’ page).

    The pageviews of course will say 37,000 hits were made to the thank you page. Odd, but I guess some people may hit refresh/ the back button and reach it again, okay. No harm, no foul.

    Here’s the tricky part. I use ‘unique pageviews’ which you said counts each unique page once per session – set up the destination exactly the same as the goal destination … and 31,000 unique hits were applied to the thank you page. Why is this one different? The unique is AT MOST once per session. Why would it be counting more than the actual goal?

    I’m wondering because I’m trying to get past data for some ‘destination pages’ before I set up goals for them. But there appears to be nothing in Google Analytics that replicated the ‘destination page goal’ number in the past.

    Reply
    1. mike_sullivan

      Make sure your time period does not trigger sampling (>500,000 sessions in total for the period, and you have the slider all the way over to most accurate instead of faster). Goals are greatly affected by sampling. Try a shorter time period to see if the problem still exists.

      Reply
  3. Ed

    How should the ‘Unique Views’ metric be used when using content grouping, sis this the best metric? Basically I want to count up how many sessions included a visit to at least one page in my content group segments? This is so I can gauge the % of visits to each section. Any clarification appreciated

    Reply
    1. mike_sullivan

      Yes, then Unique Views metric should be used like Unique Pageviews when you are working with Content Page Groups

      Reply

Leave a Reply

Your email address will not be published. Required fields are marked *