Mislevy, Almond, and Lukas (May 12, 2003) introduce novices to Evidence-Centered Design (ECD), a computer based assessment procedure that gives special attention is the roles of probability based reasoning in accumulating evidence across task performances. ECD addresses beliefs about unobservable variables that characterize the knowledge, skills, and/or abilities of students traditionally associated with psychometric models, such as those of item response theory and latent class models.

In short, What all educational assessments have in common is the desire to reason from particular things students say, do, or make, to inferences about what they know or can do more broadly.

These writers argue that off-the-shelf large group assessments and standardized tests increasingly show unsatisfactory results for guiding learning and evaluating students’ progress. Advances in technology make it possible to evoke evidence of knowledge more broadly conceived, and to capture more complex performances.

The structure undergirding ECD permits overcoming one of the most serious bottlenecks, that of making sense of complex data possible with technology based assessments.

ECD unifies the ideas of assessment theories and provides a foundation for extending probability-based reasoning in assessment applications more broadly. They note that a more general expression in terms of graphical models is indicated.

This brief overview of evidence-centered design provides the reader with a feel for where and how graphical models fit into the larger enterprise of educational and psychological assessment much as GRE is used to fix ideas.

Mobile PC education software designers likely understand the ECD model and design, and can figure out ways to link their products to ECD

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