Statistical Software: R and SAS
This chapter outlines the elementary components of the R (R Development Core Team 2014) and SAS statistical software packages. Both packages allow the user to implement powerful built-in routines or employ programming features for customization. R is an open-source, case-sensitive, command line–driven software for statistical computing and graphics. Once R has been loaded, the main input window appears, showing a short introductory message. There may be slight differences in appearance depending on the operating system. A syntactically valid R name consists of letters, numbers, and the dot or underline characters and starts with either a letter or the dot not followed by a number. Reserved words are not syntactic names. R operates on named data structures. The simplest form is the numeric vector, which is a single entity consisting of an ordered collection of numbers.