Exploration almost never results in a single plan, but rather exposes several alternatives that are promising enough for serious consideration. Evaluation of alternatives typically occurs “on paper” before an artifact is produced. Once an artifact has been produced, there is almost always an evaluation through testing by the user. Users are clearly best at assessing, through their own experience, whether an artifact actually closes the sensed gap in their experience.

— Design: Creation of Artifacts in Society by Karl Ulrich