Bounce Rates are when a visitor came, puked, and left.
Avinash Kaushik, Digital Evangelist, Google, has been known to explain the metric with this human reaction, but the idea doesn’t stop there. Looking at the raw metric for all the pages and traffic sources on your website can give you a misleading number.
Jonathan Allen, Director of Search Engine Watch asks Avinash to revisit bounce rates and explain what they mean to him.
Advertising or referral links can be poorly targeted or contain the wrong message. So your content and landing page could be brilliant, but if for example you are selling underwear on your landing page and the ad that someone clicks on is for off dog food, that visitor will turn around immediately. The alternative to your advertising being off target is that your landing page stinks.
The importance of measuring bounce rates as a KPI depends partially on what the goals of your website are. If for example your website is an ecommerce site or any site that requires an action from the user to complete the conversion, then a high bounce rate is bad because you aren’t making money.
Pure content sites like the New York Times are where the strict definition of a bounce rate gets trickier, because the user may get what they want without ever going to a second page. Avinash recommends segmenting users and paying attention to the bounce rate of specific segments that matter. On his blog he cares a lot more about new visitors as opposed to return visitors, because he is looking for new users to complete some form of microconversion: sign up for the RSS feed or the email news letter.