“Bounce rate” in Google Analytics is one of the key metrics that helps webmasters to evaluate the quality of their website traffic. Bounce rate represents the percentage of visitors who enter the site and "bounce" or leave instantly rather than continue viewing other pages within the same site. This is a great indication on how relevant the content was for the user and how engaged they were with your website.
Generally it is believed that a high bounce rate is an indication that the site entrance pages aren't relevant to the visitors because it caused them to leave the website without exploring other pages. An entry page with a low bounce rate means that the page effectively causes visitors to view more pages and continue on deeper into the web site.
But a high bounce rate is not always a sign of poor performance. A high bounce rate can also occur if a visitor came to your page, found what they came looking for and left satisfied without viewing another page. In such cases, the entry page could have a very high bounce rate, as high as 80%, yet they might still be considered successful due to having served their purpose.
Nonetheless it is still desirable and the wish of every webmaster to retain visitors on their website and get them to view as many pages as possible. But if that high bounce rate figure on your Google Analytics dashboard is bothering you, there is a way to lower it. Google calls it “adjusted bounce rate”.
You implement a small tweak to your Google Analytics code which executes an event when a user has spent over a certain amount of time on the webpage. Once the event is executed, the visitor is no longer counted as “bounce,” even though no additional pageview is recorded. Only users who have not spent a required “minimal time” on your website will be counted as a bounce.
Depending on the website, the time can range from 10 seconds to few minutes. You should decide for yourself the amount of time you consider the user to be sufficiently engaged with your website or product.
To implement the timer code, add the line function setTimeout as shown in the code below. Here the delay is set to 15 seconds.
var _gaq = _gaq || ;
setTimeout("_gaq.push(['_trackEvent', '15_seconds', 'read'])",15000);
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
var s = document.getElementsByTagName('script'); s.parentNode.insertBefore(ga, s);