Preprint
Oct 2026
Watanabe's Learning Coefficients in Item Response Theory
We study the joint-parameter two-parameter logistic (2PL) model in item response theory, in which both item parameters and respondent abilities are treated as unknown fixed parameters. We first characterize its singular structure through the Fisher information matrix. The parameterization has an inherent scale indeterm...
Joe Suzuki, Takumi Ikejiri, Yuki Kurumadani
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