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Applying Multiphase Sampling to Selecting Testlets With Constraints on Item Blocks IRT

Qian, Jiahe; Gu, Lixiong; Li, Shuhong
Publication Year:
Report Number:
ETS Research Report
Document Type:
Page Count:
Subject/Key Words:
Testlets, Item Blocks, Multiphase Sampling, Test Security, Test Assembly, Sample Size, Constraints on Parameters, Parallel Test Forms, Item Response Theory (IRT)


In assembling testlets (i.e., test forms) with a pool of new and used item blocks, test security is one of the main issues of concern. Strict constraints are often imposed on repeated usage of the same item blocks. Nevertheless, for an assessment administering multiple testlets, a goal is to select as large a sample of testlets as possible. In this study, the algorithm of multiphase sampling was applied to selecting and augmenting the sample of testlets to be administered. Several topics related to the algorithm are discussed, such as the termination of the algorithm, the dynamics of sample size, and the effectiveness of the algorithm. A real database of testlets was used in the study.

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