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Overview

The R package theta2 is an item response theory modeling software whose purpose is:

• Fit a variety of IRT models including the univariate, multivariate exploratory and confirmatory, and higher-order confirmatory models
• Specify regression models in the context of IRT with both fixed and random effects (i.e., mixed modeling)
• Simple model syntax to describe IRT models with and without regression

Documentation & Source

• The theta2 R package source code can be found at github.com/inirt/theta2

• Full documentation and tutorials can be found at inirt.github.io/doc/

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Installation

1. Since this is an R pacakge, the user first needs to install R from the R project website.

2. Once R is installed, open an R console and install the package from Github using remotes:

# remotes
install.packages("remotes")
# install from Github
remotes::install_github("inirt/theta2")

Alternatively, install from CRAN with:

install.packages("theta2")

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