Is your site less effective that you think it ought to be? One way to pinpoint possible problems is through the use of a metric called "bounce rate."

Defining Bounce Rate

A bounce is a one-page visit. "I came, I landed, I left." Bounce Rate is the rate at which bounces occur, that is, the number of bounces on a page divided by the number of people who entered the site on that page.

You can discover these metrics using a free tool like Google Analytics. (Note: In Google Analytics, if additional interaction is tracked on that single page -- such as a video being played -- the visit is not considered a bounce.)

Why Bounce Rates Matter

Bounce rates provide important clues to what's going on with your site. A high bounce rate is often a measure of "badness," while a low bounce rate is usually a measure of "goodness." When people look at only one page and leave, they are usually signaling that your site didn't meet their needs -- or at least, that's what they perceived to be the case.

Is there any situation in which a high bounce rate should not be considered awful? Yes. An example might be the home page of your blog. Someone might land, spend 10 or 20 minutes reading the ten posts there, and leave without clicking to another page. A successful visit? Yes, even though it would count as a bounce.

However, you can still generalize that high = bad and low = good. How high is "high" and how low is "low"? Unfortunately, the answer is usually, "it depends." Recently, our company did a lot of work with this topic, and saw bounce rates as low as 18% and as high as 90% in the same industry.

Bounce Rate Rules of Thumb

In general, we found that bounce rates:

In the middle, it is even harder to say "good" or "bad" without context. If you use Google Analytics, consider turning on the benchmarking feature so that you can compare your bounce rate to others, but be mindful of the privacy issues involved with such a decision -- read the terms and conditions.

How to Use Bounce Rate

We can look at bounce rate by page, by traffic type, by city -- almost by any dimension you like. Like all of analytics, if you know what you're looking for, it's easier to find it. For example, we had one site where bounce rate by US state was very important. We had a hunch that visitors from certain states were having a bad experience -- and we were right.

The job of web analysts like me is to figure out "how a site is doing." We often don't know what we are looking for until we find it. If you don't know what you are looking for, you should always look at bounce rate by medium and source (that is, how they found you) and you should look at the high and low bounce rate pages on your site.

Finally, look at the site bounce rate overall.  From this you can learn:

• Whether you are having a problem with certain kinds of traffic. For example, if you have a very high bounce rate with your paid search, you can drill down to learn if it is caused by bad keywords, bad ads, etc. 
• Whether you are having a problem with certain pages. From there, you might use Google Website Optimizer to test your site.
• Whether you have a problem on the whole site. If so, you should consider user testing. We strongly recommend the very cost-effective tool at UserTesting.com. With user testing, you'll start to understand the high level reasons visitors are unwilling to stay on your site.

Bounce rate won't answer all your questions, but it can help you pinpoint problems that, when fixed, will free your site to excel in meeting your customers' needs.