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Linking for the General Diagnostic Model GDM NAEP

Author(s):
Xu, Xueli; von Davier, Matthias
Publication Year:
2008
Report Number:
RR-08-08
Source:
ETS Research Report
Document Type:
Report
Page Count:
17
Subject/Key Words:
General Diagnostic Model (GDM), Calibration, National Assessment of Educational Progress (NAEP), Test Linking, Expectation, Probability

Abstract

Three strategies for linking two consecutive assessments are investigated and compared by analyzing reading data for the National Assessment of Educational Progress (NAEP) using the general diagnostic model. These strategies are compared in terms of marginal and joint expectations of skills, joint probabilities of skill patterns, and item parameter estimates. The results indicate that fixing item parameter values at their previously calibrated values is sufficient to establish a comparable scale for the subsequent year.

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