A&#x2F;B (or champion&#x2F;challenger as we called it in the 90s) testing is fine. The problem with these tools is that they do not alleviate the need to understand statistics.<p>A common place where people get stuck when A&#x2F;B testing is in a local minimum or maximum. For example, instead of tweaking button colors someone should instead redesign the whole form. Talking to users can help with this, but users are notoriously bad at not knowing what they really want.