library(knitr) opts_chunk$set(fig.path = "man/figures/README-")
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)
.
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