Figure 2-5. Time-on-page calculation
The time a visitor spends on a particular page or the total time he spends on your website is a good indicator of how sticky your site is and how engaged visitors are by your content. The more time a visitor spends, the more engaged he is. Both metrics, time spent on a page and time spent on the site, can reveal many details about visitors’ interaction with the site. And although they both seem straightforward, their accuracy is challenged by how they are calculated based on real data.
Figure 2-5 represents the process of a visitor navigating through a website and includes timestamps for when he enters different pages. He visits three pages before exiting the website. The time spent on page 1 is calculated by subtracting the entry timestamp of 6:00 on that page from the entry timestamp of 6:03 on page 2. As such, analytics packages will report that this visitor spent three minutes on the first page. The timestamp is essential in calculating the time spent on a page.
Given the information in Figure 2-5, can you calculate the time the visitor spent on page 3? Most analytics packages will calculate the time a visitor spends on a page only if the visitor navigates to another page on the site. Without the timestamp for a fourth page in Figure 2-5, there is no easy way to determine how much time the visitor spent on page 3. The visitor could have spent one minute or 15 minutes, but since it is not tracked, the time spent on page 3 is reported as zero.
This calculation shows the actual time spent on a page by a single visitor. The following formula shows how to calculate the average time all users spend on a particular page:
| Average time on a page = Total time spent by all visitors on the page / Number of nonexit page views |
The time spent on a page for visits that exit the site from this page is reported as zero. Thus, these visits are not included in calculating the average time on the page. Since we are excluding these visits, the accuracy of reporting is questioned. The higher the exit rate for a particular page, the less accurate the reporting of its average time. Consider two different pages on a website:
Page 1 has an exit rate of 45%, which means 45% of its visitors leave the site from that page and never navigate to another page. Since visits that result in an exit are not included in calculating the average time spent on the page, we have to exclude 45% of the visits.
Page 2 has an exit rate of 15%, which means 15% of its visitors leave the site. Again, visits that result in an exit from the website are not included in calculating the time spent on the page. In this case, we only exclude 15% of the visits from calculating the average time on that page.