The $300 Million Button is great article by Jared Spool on the subject of making a simple UX change to get real world results. The key here though, doctor was to listen to the user and give them what they wanted.
We were wrong about the first-time shoppers. They did mind registering. They resented having to register when they encountered the page. As one shopper told us, generic “I’m not here to enter into a relationship. I just want to buy something.”
Often I find myself fighting the marketing side which really wants to get the value of all the registered customer data. In fact most of the user flow documents I’ve worked on were designed with the marketing goal of getting user to register. In this case the real value was in actual sales. It’s always good to be reminded to keep things in perspective and perform user tests.