R

The R project for statistical computing

Freeware

The R Projectfor statistical computing

Software scripts and links

An introduction to psychometric theory with applications in Rfrom the R Core Team

Psychometrics in RJournal of Statistical Software

Psychometric Models and MethodsPatrick Mair & Reinhold Hatzinger, The Comprehensive R Archive Network (CRAN)

Statistics for the Social SciencesJohn Fox, the Comprehensive R Archive Network (CRAN)

Multivariate Statistics  Paul Hewson, the Comprehensive R Archive Network (CRAN)