I just launched a new product yesterday using Facebook Ads and while the Ad literally only got approved 8 hours ago (LOL) I have been looking at the data on the Analytics option on Facebook and it says my average Median Session Length is .5 seconds, or half a second, which is confusing to me because my bounce rate is 47.2% which I have read to be an average bounce rate so the numbers aren’t making sense to me.
Looking at session duration and bounce rate can be confusing because of how the two are calculated. First, bounce rate is a visit to your site with only one hit (or interaction). So if a visitor goes to the home page, then leaves without taking any other action it is considered a bounce.
However, session duration can only be calculated when more than one hit (interaction) occurs on your site. For instance, if a users hits the homepage, a time stamp is created for that his in analytics. If the user does not take any other action and just leaves the site, analytics does not know when they left because a second hit is not registered to create another timestamp, so their time on site is 0 seconds. So, bounced traffic will always have a 0 second session time, which will drop your time on site average down if you have a lot of bounces.
If you do not have a lot of traffic yet, these numbers can fluctuate greatly depending on just a few visits. How many visits are you seeing to the site so far?