grmtree: Recursive Partitioning for Graded Response Models

Provides methods for recursive partitioning based on the 'Graded Response Model' ('GRM'), extending the 'MOB' algorithm from the 'partykit' package. The package allows for fitting 'GRM' trees that partition the population into homogeneous subgroups based on item response patterns and covariates. Includes specialized plotting functions for visualizing 'GRM' trees with different terminal node displays (threshold regions, parameter profiles, and factor score distributions). The package also implements the Longitudinal GRMTree for detecting response shift in PROMs measured at two time points, embedding a constrained two-factor longitudinal GRM within recursive partitioning, with post-hoc characterization of recalibration and reprioritization. For more details on the methods, see Samejima (1969) <doi:10.1002/J.2333-8504.1968.TB00153.X>, Komboz et al. (2018) <doi:10.1177/0013164416664394> and Arimoro et al. (2025) <doi:10.1007/s11136-025-04018-6>.

Version: 0.2.0
Depends: R (≥ 4.1.0), partykit (≥ 1.2-9), mirt (≥ 1.36.1)
Imports: stats, graphics, grid, ggplot2, rlang, strucchange
Suggests: hlt, dplyr, magrittr, testthat (≥ 3.0.0), knitr, rmarkdown, psychotools, psychotree, psych
Published: 2026-07-02
DOI: 10.32614/CRAN.package.grmtree
Author: Olayinka I. Arimoro ORCID iD [aut, cre], Tolulope T. Sajobi [aut], Lisa M. Lix [aut], Matthew T. James [ctb], Maria Santana [ctb], Emmanuel Ugochukwu [ctb]
Maintainer: Olayinka I. Arimoro <olayinka.arimoro at ucalgary.ca>
BugReports: https://github.com/Predicare1/grmtree/issues
License: GPL-3
URL: https://github.com/Predicare1/grmtree
NeedsCompilation: no
Materials: README, NEWS
CRAN checks: grmtree results

Documentation:

Reference manual: grmtree.html , grmtree.pdf
Vignettes: GRM Forests for Robust DIF Detection (source, R code)
Getting Started with the grmtree Package (source, R code)
Response Shift Detection with the Longitudinal GRMTree (source, R code)

Downloads:

Package source: grmtree_0.2.0.tar.gz
Windows binaries: r-devel: grmtree_0.2.0.zip, r-release: grmtree_0.1.0.zip, r-oldrel: grmtree_0.1.0.zip
macOS binaries: r-release (arm64): grmtree_0.2.0.tgz, r-oldrel (arm64): grmtree_0.2.0.tgz, r-release (x86_64): grmtree_0.2.0.tgz, r-oldrel (x86_64): grmtree_0.2.0.tgz
Old sources: grmtree archive

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