The built in "split test" feature lets you compare the effectiveness of one page versus another.
Usually a sales or offer page are most often tested in this way.
The split test control page is located in the Utility section of your site's control panel:
The main screen shows you any existing split tests that are running as well as the number of page views and conversion rates for those pages:
There is a link to create new split tests. In there you can specify which 2 pages you wish to test against each other. The original page vs. the alternate page. Put in the URLs in the appropriate boxes.
You can also track the conversions of each page. Normally for example page 6 on your site is the "welcome" page for brand new members. If you were testing a sales page you could use the "welcome page" url as the conversion page. The split test keeps track of which of the 2 test pages they came from and then credit the appropriate page with the sale. In this way you can tell over time which page is converting better for you.