R is a free programming language designed specifically for statistical calculations and plotting resulting graphs and charts. It is available and free for use under the GNU General Public License. Versions for most computer platforms exist. R is an interpreted language, command line interaction is a usual means of engaging with it, although several GUI (Graphical User Interface) based IDEs (Integrated Development Environments) exist as well. R supports packages which enables developers to extend the language by adding libraries of R code. R is a procedural programming language supporting functions. Generally R is seen as a well featured alternative to proprietary packages such as STATA and SPSS.
– http://www.r-project.org/ Accessed 28 October 2015.
– http://darwin.eeb.uconn.edu/uncommon-ground/2013/09/a-gentle-introduction-to-r.html Accessed 28 October 2015.