So…we've visited customers and gathered thousands of observations. Now what? Do we send our giant spreadsheet around and call it good?
No way. Research without analysis is like trying to make earrings out of ore. We need to find patterns in the data, assess the relative importance of those, and figure out a way to communicate the important design drivers to the team.
Design Criteria are an effective way to crystallize research findings into something people can understand. They are effective in two major ways. First, they help the team generate ideas for solutions, with confidence that the reasoning behind those ideas is based in real human behavior. Second, they are great variables to use when it comes time to evaluate design alternatives; generally, the designs that satisfy design criteria more effectively have a better chance at successful adoption (assuming they don't cost too much more). That is why I call design criteria the "golden nuggets" of research - they are the pure distillation of the characteristics that will make the final offering great.