Among the many tasks designers must perform, evaluation of concepts based on performance criteria is fundamental. A formal evaluation of a design defines a measurement of the design: an assessment reflected by real valued numbers. A measurement requires some basic a-priori information from the designer. In particular, a base-point design is required from which the remaining designs are relatively measured. Also, a metric reference design is required to compare the deviation of each remaining design from the base point design. Given these two reference designs, any other design can be evaluated numerically. Such engineering methods as concept selection charts, QFD, optimization, and many current research methods in engineering design use these measurement fundamentals to evaluate designs. Measurement theory provides a common framework to discuss solution evaluation within all of these methods. Further, the minimum formalization needed to make evaluations among design configurations is also demonstrated.