> Amazon.com is likely the most a/b tested piece of software on the planet. It is ugly and clunky because that's what _works_ - same with Alibaba and Yahoo JP.

This was on the HN frontpage yesterday: "Be good-argument-driven, not data-driven" https://news.ycombinator.com/item?id=32651763

I’ve seen countless bad decisions being taken because the A/B test was badly done. You can’t assume that some decision was good JUST because they A/B-tested it.