University of North Texas 
R, or GNU-S, is free; note that there is no qualification - it is a completely free, statistical
package that provides an impressive array of methods for data analysis, interpretation,
and graphical display. Based on the S language first developed by Bell Labs decades
ago, it is quite simply the most advanced of what we have access to of the general
purpose packages for academic research, and for anyone wanting to keep up with the
times it is the package of choice, bar none.
Watch this video: What is R?
R however does take a bit to become comfortable with compared to some packages as it is primarily command line driven. However, it should be stressed that one can use it in a very applied fashion, only taking from it what is necessary for the data situation at hand and there are many packages that offer dropdown menu capability. In other words, you do not have to become a computer programmer to take advantage of its functionality. In the end though, if you want to use methods that have been developed in the last 30 years and take advantage of today's computing power, this is the package for you, and the big packages like SAS and SPSS lag far behind its capabilities for the academic researcher.
S-Plus can be seen as a proprietary version of the S language, with its most noticeable difference being that it comes with a sophisticated gui out of the box. S-Plus and R are very compatible with one another in most respects, however R has near daily updates and many, many more packages and offerings.
Other Notes
You do not have to come to us to obtain R. It is free to all.
SPSS, starting with version 16, has the ability to run R scripts as long as R version
2.5 (or newer) is installed on the machine.
Research Computing Services' Do It Yourself Introduction to R course
Research Computing Services' S-plus & R Short Course class materials & links
R
Download Site for the Latest Binary and R Packages
- The Comprehensive R Archive Network (CRAN): main site for everything R
- Download
- Introduction to R
- CRAN R Package Descriptions - Pdf manuals available for packages
- R Packages Organized by Topic - Organized by discipline and methodology
Free R Books and Tutorials
- LinkedIn Learning has a few tutorial videos dealing with R, such as:
- Arepository of R related blogs and blog posts R-bloggers
- Kickstarting R - An HTML Beginners guide
- R for Beginners
- Quick R: an R website for SAS/SPSS/Stata Users
- ...more resources
Attention Mac Users: You should review John Fox's installation page -- the Mac section; located at: http://socserv.socsci.mcmaster.ca/jfox/Misc/Rcmdr/installation-notes.html.
Script editor
- Tinn-R: don't let the command line get you down, use R's built in script-editor at the very least, but Tinn-R has many more features.
Web Interfaces to R Web Servers and Example R Scripts
- R Web Interface - Run R programs from any machine through the web
- Example R Scripts - Some of these scripts run on a server and results are communicated thru a web browser
Articles Using or Regarding R
R and Survey Analysis
R, R(D)COM and Excel
R News
The R Journal
S-Plus
General links
- Insightful Website
- Getting started with S-Plus
- S-Plus Tutorial
- S-Plus 8 Users Guide
- S-Plus 8 "Guide Statistics" vol 1, vol. 2
- S-Plus Official Documentation
- More links here
S-PLUS Student Edition Download - Free
- Student Edition - This version of S-Plus has a 20,000 cell or 1,000 row limitation; is only for educational use; is good for only one year; and is a rather large download (100+ meg).
- If you prefer a cd, one can be purchased at the bookstore.
S-PLUS Free Experimental Libraries and User Contributed Libraries
- Research Libraries - a variety of free addon packages
- User Contributed Libraries