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January 8, 2008

I was thinking the other day about the relationship between exit rate and bounce rate. It's often assumed that there's some type of mystical relationship between these two metrics, so I thought it would be worthwhile to dig deeper into this relationship to see what's actually going on.

First, we can define these measurements using rather simple equations.

exit rate = exits / pageviews
bounce rate = bounces / entrances

Now if we think about it, every visit to your site has an entrance. And unless you have visitors who stay active on your site 24/7, taking 15 minute power naps in lieu of actual sleep just to keep their current session alive, every visit to your site will also have an exit. Therefore, if we're talking about the exit rate and bounce rate of your site, we can say that entrances = visits = exits and make the appropriate substitutions in the above equations:

exit rate for the site = visits / pageviews
bounce rate for the site = bounces / visits

This would seem to indicate that if the number of visits increase then exit rate will increase while bounce rate will decrease, and alternatively, if the number of visits decrease then exit rate will decrease while bounce rate will increase. Of course, this assumes that visits are independent of both pageviews and bounces, which they aren't. So to understand this relationship, we have to think about the quality of visits that we're getting to the site.

If the additional visits to the site were of the same quality as we were getting before, this would mean that the average pageviews for the site would be the same as the previous visits. Average pageviews, however, is the reciprocal of exit rate for the site, so exit rate would remain constant in this case. We would also expect roughly the same percentage of single pageview visits for this extra traffic, so bounce rate would also remain constant.

If, however, we obtained higher quality traffic, then average pageviews would go up, so exit rate would go down. Similarly, we'd expect a higher percentage of multiple pageview visits, so the bounce rate would also go down. Obviously, if we obtained lower quality traffic, then we'd expect exit rate and bounce rate to go up instead.

So how close is this relationship then? If we're given a particular bounce rate or exit rate, for instance, can we reasonably predict the range of the other metric? Let's start with the relationship between bounce rate and exit rate for a single page.

If you have a 0% bounce rate for a page, this tells you nothing about its exit rate. If the bounce rate for a page is greater than 0%, you know that your exit rate will also be greater than 0%, but other than that, anything goes.

If the exit rate for a page is 0% or 100% then the bounce rate for that page is 0% or 100% respectively. An exit rate for a page of anything other than 0% and 100%, however, tells you nothing about bounce rate. So aside from a few extreme cases, the relationship between these two metrics for a page is just about zilch.

So on the single page level, knowing one of the metrics in question gives us little to no information about the other metric, except in certain extreme cases. So let's examine this now at the site level.

If your site has a 100% bounce rate (egads!) it will also have a 100% exit rate. If the bounce rate is less than this, however, all you know about your site's exit rate is that it's greater than 0% and less than or equal to 1 / (2 - Bounce Rate).

Similarly, a site with an exit rate of 100% (the horror!) will have a bounce rate of 100%. An exit rate of 0% for a site is impossible unless no one visits your site. Other than that and the bounce rate for your site must be less than 100% and greater than or equal to 2 - (1 / Exit Rate) or 0%, whichever is greater.

Looking at these relationships raises an obvious question: why would we want to look at maximum possible exit rates and minimum possible bounce rates anyway? The answer is that we wouldn't. There are much better uses of our time, such as looking at trends.

So, it turns out that bounce rate and exit rate have less to do with each other than we might think. It might even be best to think of them as entirely separate metrics. My intention over the next few weeks is to write more about bounce rate and exit rate to clear up any confusion as to what these metrics mean and talk about how we can use them.

So please, feel free to leave any comments about this topic.

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Comments

Jeremy Aube, Google Analytics Support Tech said:

@tcxo: Your content traffic should all be under the keyword (content targeting), so you can add an exclude filter to remove this traffic from your reports:

Filter Name: Remove Content Targeting Traffic
Filter Type: Custom filter->Exclude
Filter Field: Campaign Term
Filter Pattern: \(content targeting\)
Case Sensitive: No

You'll probably want to create an additional profile that includes just this traffic so that you can still monitor it.

September 25, 2008 12:43 PM

Jeremy Aube, Google Analytics Support Tech said:

@Cheryl: For Google Analytics, a bounce is a session with only one visitor interaction with the site. Usually, visitor interaction is measure by pageviews, but this interaction can also be measured with events, transactions, etc.

If your bounce rate has suddenly dropped to 0%, this means something is in your Google Analytics Tracking Code that is causing at least two interactions or hits when a visitor comes to your site. You may have multiple sets of Google Analytics Tracking Code on the site.

Maybe the new blogger has an automatic integration with Google Analytics that you're using, plus you've manually put Google Analytics Tracking Code on the site yourself. Another possibility is that you're redirecting visitors from the old blogger to the new blogger, but a pageview is occurring on the old blogger before the visitor is redirected.

The bottom line is that something is causing two Google Analytics hits to occur right off the bat, so you should remove the code that causes the extra hit in order to see your bounce rate correctly.

March 10, 2009 8:05 AM

Jeremy Aube, Analytics and Optimization Specialist said:

@Alexia: A bounce rate of 0% for a page might also indicate that the page was simply never a landing page for your visitors. You would have to check the landing pages report in order to see the number of entrances for the page and get the proper context.

It's very unusual for a heavily used landing page to have a bounce rate of 0%. This usually likely indicates some kind of tracking issue such as multiple _trackPageview calls on the page or possibly an event tracker that's always called on the page

July 30, 2009 8:37 AM

Jeremy Aube, Analytics and Optimization Specialist said:

@Alasdair: Yes, by default if a visitor reads the latest blog on your home page and then leaves the site, they will be considered a bounce in your Google Analytics reports. So in this case, a bounce rate of 50% makes a lot of sense.

There are a few options in order to get a better sense of your actual bounce rate. One is to show just a portion of the latest blog post and have visitor's click if they want to read more. That's what we do for most of our blog posts. The other option is to set a pageview or event to fire off after a given amount of time. Ten to fifteen seconds is probably sufficient to conclude some type of engagement with the site.

August 1, 2009 11:47 AM

Jeremy Aube, Analytics and Optimization Specialist said:

@Jay: The short answer is "Yes", assuming that the page on your site is the first pageview of their visit. There are some important exceptions:

1. If a visitor clicks an outbound link, but hits the back button to come back to your site within 30 minutes, that will not count as a bounce/exit.
2. If the clicking on the link results in a new tab/window and the visitor closes that tab/window and resumes navigation within 30 minutes, that will not count as a bounce/exit.
3. If you track clicks on that link using virtual pageviews, event tracking, outbound link tracking, etc., then there will be no bounce regardless of whether or not the visitor returns to the site.

October 21, 2009 8:57 AM

Jeremy Aube, Analytics and Optimization Specialist said:

@Chris:

Answer: A

Reason: The last pageview always gets the exit. Since you're tracking the banner ad as an event, this is considered a second interaction with your site. A bounce only occurs for visits with a single interaction, therefore this is not considered a bounce.

December 14, 2009 8:59 AM

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