Friday 30 January 2009 | 16:03
In the past we've received a lot of feedback from our users who have implemented the _setVar method requesting that custom visitor segments not affect bounce rates. You've asked for it and we've listened! Today we're modifying this feature so that the _setVar method no longer counts as an interaction hit with the result that you may see higher bounce rates and more accurate time on page metrics in your reports.
As a refresher, Google Analytics calculates bounces and durations based upon interaction hits. Now, interaction hits will only include pageviews, events, transactions and experiments (such as with Google Website Optimizer). Here's more on how this change to the _setVar method could affect your data:
Higher bounce rates in your reports
Let's say that you've used the _setVar method on your landing pages to segment member vs. non-member site visitors. Previously, if a visitor came to your site and triggered the _setVar call, but viewed only one page, this would not be counted as a bounce. With this change the user defined call will not send an interaction hit and overall bounce rates will increase as this single page visit will now be counted as a bounce.
More accurate time on page metrics
Time on page metrics are normally counted by the difference in time stamps which are set by interaction hits. Prior to this change, using _setVar would cause Google Analytics to calculate the time on page metric between the time of the pageview hit and the interaction hit of the user defined variable. Now, as user-defined hits are no longer counted as an interaction hit, time on page metrics should more accurately reflect the time between one pageview and the next.