Average session duration is a PPC metric that represents amount of time users spend on your website before quitting the session. We say “represents” as opposed to “measures” because the way Google calculates this metric isn’t a true measurement of session duration and this can lead to some confusion.
In this article, we explain what Avg. Session Duration really tells you in Google Ads and how you can use the metric to improve campaign performance.
How do you calculate average session duration?
The calculation itself for Avg. Session Duraiton is pretty straight forward. Google simply divides the total time tracked across sessions being measured and divides this figure by the total number of sessions measured.
Average Session Duration = Session Duration / Sessions
No surprises so far, then, but the confusion about average session durations comes down to how Google tracks the time users spend on each page.
To clear up any potential confusion, we have to discuss how Google calculates a different metric. As we explain in our article on Avg. Time on Page, Google can only log the time users spend on any given web page when they click through to another one.
This means the Avg. Time on Page metric doesn’t include data for instances where the page being measued is the last page in the session.
Likewise, the Avg. Session Duration metric doesn’t include the data from the final page of the session because Google can’t log the time spent on the exit page. The issue is, every session has an exit page and the loss of this data can have a drastic impact on the accuracy of this metric, especially for sessions with a small number of page visits or where a lot of time is spent on the exit page.
In some caes, this can lead to the Avg. Session Duration starting from any given URL being lower than the Avg. Time on Page reading for the same page.
This is the results of multiple bounce sessions, where the user exits before vising a second page, which record a session duration of zero seconds but increases the sessions number in the Avg. Session Duration by +1 each time. If this happens often enough, you can end up with Avg. Session duration readings lower than Avg. Time on Page for the same URL.
What does average session duration tell us?
As a standalone metric, average session duration doesn’t offers a great deal of insight because you have to look at other metrics to understand what the numbers are really telling you. As we touched on in the previous section, you could at Avg. Session Duration for session starting with a bounce that has a high bounce rate and assume your PPC campaign is performing worse than it actually is.
In some caes, this can be a red flag but you have to consider the potential inaccuracy of average session figures in Google Ads, as well as the fact that bounces aren’t always a bad thing 0 eg: visitors convert and leave without visiting another URL.
To figure out exactly what your Avg. Session Duration figures say, you have to compare them with other metrics – namely:
- Pages per session
- Avg. time on page
- Exit %
- Bounce rates
- Conversions
- Loading times
Be wary of looking at Avg. Session Duration alone and reading too much into the numbers. Without comparing this metric with other session data, it’s easy to draw the wrong conclusion and make rash decisions that could casue more harm than good.
What are the most important PPC metrics?
If you want to find out the most important PPC metrics and KPIs to focus on, we have the perfect guide for you: What Are The Most Important KPIs For PPC?
You can also reach out to our PPC team if you need help with optimising your campaigns to maximise performance and improve the profitability of your paid advertising strategy. Call us on 0161 870 2580, email us at info@hotclickmarketing.co.uk or catch us on Twitter via @hot_click with any questions you have.