The errum package provides a high-performance implementation of the Exploratory reduced Reparameterized Unified Model (ErRUM) described by Culpepper and Chen (2018). Development of this model followed from Chen et al. (2018)’s work on estimating the Q-matrix within a cognitive diagnostic model (CDM). With the package now on CRAN, this is the first time an exploratory model has been made available publically! For more information, please see the full NEWS release …