The CTRL Lab supports the following Open Source alternatives to proprietary statistics packages. In addition to visiting each project's web site copies are available through https://mynet.american.edu (requires an AU login and password) in the folder J:/classes/prepared.
The open source equivalent of this software is Gretl. It supports a number of languages and performs a variety of linear analyses.
R provides a wide variety of statistical (linear and nonlinear modelling, classical statistical tests, time-series analysis, classification, clustering, ...) and graphical techniques, and is highly extensible. One of R's strengths is the ease with which well-designed publication-quality plots can be produced, including mathematical symbols and formulae where needed.