Time metrics in Google Analytics are the terribly confusing.
A report with Average Time on Site and Average Visit Duration will paint a very different picture. Which leaves you wondering – which metric is the best one to focus on? You know the feeling, you get stuck into a report and your average visit duration is a mere :40, ‘oh crap’ you think, but then average time on page swoops in like a dash of saving grace and boasts an average time of 3:09. ‘I’ll just take average time on page,’ you think.
Neither metric is superior over the other. The fact that they are calculated are flawed will skew your analysis with inaccurately short or lengthy times. Google looks for timestamps between interactions (pages and events) to calculate these – the difference between the time a person lands on one page then moves onto the next page.
Google Analytics cannot capture time on exit pages or bounced visits. That is the time a visitor spends on the last page that they view before they leave your site, or visitors that only view a single page in a visit. Say a person lands on your site and peruses the homepage for 30 seconds before seeing something that takes their interest, spends three minutes on the next page, and then leaves. The last three minutes they spent reading is not captured as it is last page viewed in the visit. The average time spent on site is reported as 30 seconds.
Average Time on Page does not include exits or bounces in its calculation. So the time can appear much higher or lower than Average Visit Duration. In the above examples that is the 3:09 time.
Average Visit Duration does include bounces, but still it cannot determine the actual duration of bounces or exits. So again, this time may appear much lower than Average Time on Page. That is the :40 time.
One way to get a better picture is through event tracking. By setting up custom event tracking on elements of pages where visitors would click onto, you can gain timestamps on interactions. So if a person viewed only a single page (bounce) yet clicked pieces of the page, the time would be reported as the difference between those interactions and not as 0:00 (a bounce). However this would still not be 100% accurate.
Its important not to stress on time metrics, but rather understand their limitations as you analyze the performance of the site, holistically. The best way to view success on Google Analytics is by focusing on the key actions you want visitors to take. These are events and conversion goals in reports. If it is sales is the goal then focus on conversions paths and use time metrics to support your argument.