Many companies in the A/B testing and optimization space publish a lot of resources in the form of blog posts, case studies and white papers that are well researched and based on real metrics. Here are some links to get started.
http://monetate.com/resources/
http://monetate.com/blog/
(Disclosure: I work at Monetate!)
http://visualwebsiteoptimizer.com/split-testing-blog/
http://visualwebsiteoptimizer.com/case-studies.php
http://blog.optimizely.com/
http://unbounce.com/blog/
