R is a programming language and environment designed for statistical computation. It is an open source project and free for anyone to use. Its user base has grown rapidly and it challenges SPSS as the de facto statistical tool.
Also used in hcistats2e: Chap. 1: page 4; Chap. 8: page 98; Chap. 14: page 164; Chap. 15: page 188
Used in glossary entries: SPSS
Links:
r-project.org: The R Project for Statistical Computing