Assessment of Complex Performances: Limitations of Key Measurement Assumptions

Why do we assign numerical ratings when assess-ing complex performances? And what is the meaning and usefulness of those ratings given the nature of these performances and the multiplicity of as-sessment purposes? These were the key questions we grappled with in devel-oping an assessment system to be used for national certifi-cation of accomplished teachers. Along the way, our work became entangled with philosophical, political, technical, and practical problems that led us into relatively uncharted territories. We worked with definitions of accomplished teaching, for example, as a domain of assessment in a pro-fession influenced by competing and often radically differ-ent ideologies. Our goal was the creation of an assessment procedure to support certification decisions, to change teaching practice, and to evaluate complex performances in professionally, technically, and administratively acceptable ways. In the process, we uncovered some of the tensions that exist between the various stakeholders involved and were provided with opportunities to examine the broader context of assessment and its instrumental nature. This work also led us to examine some key assumptions that are held in the field of measurement and their implications for the multiple assessment purposes that we had to consider. The system we were developing was to be used by the