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Evaluating the Comparability of Paper-and-Pencil and Computerized Versions of a Large-Scale Certification Test PPT CBT DIF

Puhan, Gautam; Boughton, Keith; Kim, Sooyeon
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Report Number:
ETS Research Report
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Page Count:
Subject/Key Words:
Paper and Pencil Tests (PPT), Computer-Based Testing (CBT), Differential Item Functioning (DIF), Item Impact, Standardized Mean Difference


The study evaluated the comparability of two versions of a teacher certification test: a paper-and-pencil test (PPT) and computer-based test (CBT). Standardized mean difference (SMD) and differential item functioning (DIF) analyses were used as measures of comparability at the test and item levels, respectively. Results indicated that effect sizes derived from the SMD were small (d < 0.20) and not statistically significant (p > 0.05), suggesting no substantial difference between the two test versions. Moreover, DIF analysis revealed that reading and mathematics items were comparable for both versions. However, five writing items were flagged for DIF. Substantive reviews failed to identify format differences that could explain the performance differences, so the causes of DIF could not be identified.

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