You can install the package (or upgrade to the latest official release version) directly within R by typing:
(assuming an internet connection and appropriate access rights on the computer). R will then download the package from CRAN (the Comprehensive R Archive Network) and automatically install it (or upgrade to the newest version if the package is already installed).
Alternatively, you can download the source files or a Windows or MacOS X binary from CRAN and install the package manually. See the R Installation and Administration manual for more details on how to install packages this way.
Once the package is installed, you can load it with:
For an overview and introduction to the package, just type:
On this website, you can also find some more information on how to obtain further documentation and help when using the package.
After installing the devtools package with
install.packages("devtools"), the development version of the metafor package can be installed with:
This approach builds the package from source based on the development branch on GitHub.
Note that the version number of the development version is the same as that of the next upcoming official release. However, the actual code may still change before the next official release is made available via CRAN.