Overview
R. Darrell Bock (1927–2019) was a psychometrician (University of Chicago), a central figure in item-response theory, multivariate analysis of categorical data, and educational measurement, and a developer of the BILOG / TESTFACT estimation software.
Key Contributions / Features
- Marginal maximum likelihood via EM (Bock-Aitkin 1981): the practical estimation method for general IRT models — integrate out ability, maximize the marginal likelihood by EM with quadrature.
- Full-information factor analysis (Bock-Gibbons-Muraki 1988): multidimensional IRT / dichotomous factor analysis, implemented in TESTFACT.
- Nominal-categories and multi-category IRT models (Bock 1972).
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