There are two different optimization techniques that you can use to evaluate potential modifications of your pages:
A/B testing - divides incoming traffic between two or more different versions of a page. Each version is a separate document in the content tree. Results are tracked for each page variant as a whole, meaning that the combined effect of all changes made to the given page is measured.
Multivariate testing (MVT) - allows you to make multiple modifications to the content of a single page and monitor the effect that specific changes have on the behavior of visitors.
By following the links above, you can find sample pages that use the corresponding type of testing.