The goal of dcm2 is to provide a generic function for calculating the M2 statistic described by Liu et al. (2016). The package provides native support for models estimated with GDINA, but package authors can create methods for different classes of models.
You can install the release version of {dcm2} from CRAN:
install.packages("dcm2")
To install the development version from GitHub use:
# install.packages("remotes")
remotes::install_github("atlas-aai/dcm2")