Actual metrics/analytics supporting consistent/standardized user experience

Question

I am looking for actual studies/analytics type data (real numbers) concerning the use of a standardized or consistent (read: accessible and beautiful) user experience / user interface.

Specifically this information will be cited to support standardizing and reworking an existing (hideous) web application, but I'm pretty certain that customer retention and good user experience metrics apply across the board.

If this is not programming-related-enough, I apologize and will accept votes to close.

EDIT: It seems I may be using incorrect terminology. To clarify a bit, based on answers so far, I'm looking for "the benefits of good design" and "quantitative research demonstrating its advantage". I think combining those two quotes sums it up nicely.

Answer 1

The gold standard for empirically supported standards for web usability is usability.gov . Each standard includes references to quantitative research demonstrating its advantage.

Answer 2

This is all a very touchy feely data anyway.

It really is only relevant to you when it's applied to your average user of your product. Also time plays a factor. It used to be that the main problem was getting people who never used computer to use a computer in there daily work life. Nowadays almost everyone uses computers (and mostly windows based computers). So the focus, I believe, has changed from away from low level standardized user interfaces into flow, feature discoverability, user experiences, etc, etc.

So I don't see how any kind of "public" data will help you in any way unless you conduct usability testing with a range of common users with your products and base your facts off that.