Mystery Powders: An Application Of The Padi Design System Using The Four-Process Delivery System (Padi Technical Report 15)


Seibert, G., Hamel, L., Haynie, K., Mislevy, R., & Bao, H. (2006). Mystery Powders: An application of the PADI design system using the four-process delivery system (PADI Technical Report 15). Menlo Park, CA: SRI International.


This report illustrates how the general principles and structural components of the PADI framework were applied to a Mystery Powders assessment demonstration project that was computer-based. The report begins with brief overviews of the Mystery Powders assessment and the PADI design framework. We then describe the classic hands-on Mystery Powders chemistry experiment in more depth, our team’s objectives in implementing a computer-based version of the task using the PADI design system and four-process delivery architecture (Almond, Steinberg, & Mislevy, 2002), the differences between the original and the computer-delivered assessments, and the technical challenges we faced. The PADI synopsis describes the design layers in the PADI framework, briefly introducing key design structures in each layer. These layers are domain analysis, domain modeling, conceptual assessment framework, assessment implementation, and assessment delivery. For purposes of our demonstration, a computerized adaptive test (Wainer, 2000) was presented that enabled an examinee to work through a series of Mystery Powders tasks. Through the logic of Lord’s (1971, 1980) “flexilevel” adaptive testing scheme, a harder task was presented after a successful solution and an easier task was presented after an unsuccessful solution. The body of this report addresses the design and technical issues that arose in the implementation of a computer-based interactive assessment, carried out with the PADI design system and cast in the four-process delivery architecture.

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