#  hIRT: Hierarchical Item Response Theory Models 

 



An R package implementing hierarchical item response theory (IRT) models where both the mean and the variance of latent preferences (ability parameters) may depend on observed covariates ([*Zhou 2018*](/publications/hierarchical-item-response-models-analyzing-public-opinion)). The current implementation includes both the two-parameter latent trait model for binary data and the graded response model for ordinal data. Both are fitted via the Expectation-Maximization (EM) algorithm. Asymptotic standard errors are derived from the observed information matrix. Available at [*https://cran.r-project.org/web/packages/hIRT/*](https://cran.r-project.org/web/packages/hIRT/)



 



 

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