How Bounce Rate, Time On Site and New Visitors Are Calculated In Google Analytics
I often come across people who misunderstand exactly what “bounce rate” defines in Google Analytics, why so many visitors seem to spend less than 10 seconds on their site or how much they should trust the information about how many “new” visitors they have had. I thought I would provide some explanations of how this data is gathered and calculated, as it may help explain your Analytics reports a little better and maybe assuage some of your fears!
The correct definition of bounce rate is the percentage of visits that only visited a single page. It is not related to how long the visitor spent on that page, for reasons that will become clear below. A bounce could be someone viewing a page for any length of time, although it is likely that the majority of visitors not sufficiently engaged to view more than one page will leave pretty quickly, unless you have a lot of information on one page or the sort of content that people want in isolation from the rest of your site (e.g. news, free stuff, a “call us now” landing page, or your latest blog post). An average bounce rate is around 40%.
Time On Site
Time on site (or page) is calculated by subtracting the time of the second page view from the time of the first. So, if I view a page at 10:02:53 (two minutes and 53 seconds after ten), then click to view my next page on the same website at 10:03:23, Analytics will calculate that I have been on the website for 30 seconds. If I then leave the website after viewing the second page, that will remain my total length of time on the website and I will have viewed the second page for zero seconds, because there is no time for Analytics to subtract 10:03:23 from (the time of the second page view).
It is for that reason that any bounces from your website (single page visits) are by definition zero second visits, meaning that the 0-10 Seconds segment in your Engagement (Visit Duration) report will always be at least as high as your bounce rate. Similarly, the final page of every visit to your site is zero seconds too.
So, “new visitors” are any visitor that doesn’t have the cookie in place, which of course means that they might not be “new” at all. If they have deleted all their cookies, or are using a different machine, they will be new regardless. Google Analytics uses first party cookies, which means they are much less likely to be deleted by browsers and anti-malware programs. Google’s Analytics Evangelist Avinash Kaushik suggests a 3%-5% deletion rate.
Nevertheless, it is inevitable that whatever proportion of “new” visitors Analytics shows, the reality will be that some of them are really returning visitors.
It’s important to have a handle on what these stats really tell you, as they are likely to figure in your conversion rate optimisation efforts, amongst other things. Talk to us today if you want to know more!