dwnominate provides a simplified R interface to the DW-NOMINATE roll
call scaling program, based on the Fortran source code available at
Keith Poole’s website.
DW-NOMINATE (Dynamic Weighted NOMINAl Three-step Estimation) estimates dynamic models of legislator ideology using roll call votes, and can efficiently estimate static ideology models across multiple legislative sessions. The results can be used to measure legislative ideology and polarization over time.
Installation requires a Fortran compiler as well as BLAS and LAPACK
libraries. On Windows these are conveniently available as part of
Rtools. MacOS includes
BLAS and LAPACK, so it only requires installing a Fortran compiler. I
recommend following the advice provided by CRAN
here. On Linux these
will be installed with the r-base-dev library (or the equivalent for
your distribution).
Once the dependencies are satisfied, the package can be installed from R by running:
install.packages('remotes')
remotes::install_github('wmay/dwnominate')DW-NOMINATE is run via the dwnominate function, which takes as its
main argument a list of rollcall objects from the
pscl package. The package
includes data from the New Hampshire State Senate for use in examples.
library(dwnominate)
data(nhsenate) # a list of `rollcall` objects
results <- dwnominate(nhsenate)
plot(results)
The results are returned as a dwnominate object with estimates of
legislator and roll call coordinates. Get detailed information about
DW-NOMINATE options with ?dwnominate and help(package=dwnominate).
Please use the citation provided by Zenodo: