Evaluation in its simplest form is the act of ascertaining the amount, value, or effectiveness of an object or action. In this informal sense, it is an activity that is exceedingly common and nearly universally practiced. Most everyday evaluative actions involve relatively low cost items or activities and can, therefore, afford to lack the scrupulousness of a systemic methodology that is desired when evaluating something of more consequence. The evaluative rigor a person might use when acquiring a house, for example, will likely be substantially different than that used when purchasing a piece of fruit from a market.

Professional educational evaluation needs to be even more scrupulous. A disciplined system informed by guiding principles helps to ensure the quality and consistency of the evaluative process, a ...