Increased conversion is one of the strongest ROI arguments for better user experience and more user research. Track over time, because it's a relative metric.| Nielsen Norman Group
1073 design guidelines to improve conversion rates and customers' shopping experience. 13 volumes, with more than 3100 screenshots that worked or failed in user testing.| Nielsen Norman Group
Computing the net present value (NPV) lets you estimate the most profitable level of usability investment. For big projects, expensive usability can pay off.| Nielsen Norman Group