A resource from the National Cancer Institute:Research-Based Web Design & Usability Guidelines
The “Strength of the Evidence” scale provides designers and developers with an indication of how seriously they should consider each guideline. A five-point scale is used to denote the “strength of the evidence” related to each guideline. The more valid the studies directly supporting a guideline, the higher the “Strength of the Evidence” metric. For example, scores of four or five are most meaningful, and can be implemented with confidence that they will help improve the Web site. [Research-Based Web Guidelines: How To Use This Site]
