Free statistical Packages1

OpenStat -- a general stats package for Win 95/98/NT, developed by Bill Miller of Iowa State U, with a very broad range of data manipulation and analysis capabilities and an SPSS-like user interface. Bill also has provided an excellent downloadable textbook in the form of Adobe Acrobat files.

SOFA (Statistics Open For All) -- an innovative statistics, analysis, and reporting program. Available for Windows, Mac and Linux systems. Has an emphasis on ease of use, learn as you go, and beautiful output. Check out list of features.

ViSta -- a Visual Statistics program for Win3.1, Win 95/NT, Mac and Unix, featuring a Structured Desktop, with features designed to structure and assist the statistical analyst.

PSPP -- a free replacement for SPSS (although at this time it implements only a small fraction of SPSS's analyses). But it's free, and will never "expire".  It replicates the "look and feel" of SPSS very closely, and even reads native SPSS syntax and files!  Some other features...

• Supports over 1 billion cases and over 1 billion variables.
• Choice of terminal or graphical user interface; Choice of text, postscript or html output formats.
• Inter-operates with Gnumeric, OpenOffice.Org and other free software.
• Easy data import from spreadsheets, text files and database sources.
• Fast statistical procedures, even on very large data sets.
• No license fees; no expiration period; no unethical “end user license agreements”.
• Fully indexed user manual.
• Cross platform; Runs on many different computers and many different operating systems.
  Note: For Windows installer, click here.

OpenEpi Version 2.3 -- OpenEpi is a free, web-based, open source, operating-system-independent series of programs for use in public health and medicine, providing a number of epidemiologic and statistical tools. Version 2 (4/25/2007) has a new interface that presents results without using pop-up windows, and has better installation methods so that it can be run without an internet connection. Version 2.2 (2007/11/09) lets users run the software in English, French, Spanish, or Italian.

Statext -- Provides a nice assortment of basic statistical tests, with text output (and text-based graphics). Capabilities include: rearrange, transpose, tabulate and count data; random sample; basic descriptives; text-plots for dot, box-and-whiskers, stem-and-leaf, histogram, scatterplot; find z-values, confidence interval for means, t-tests (one and two group, and paired; one- and two-way ANOVA; Pearson, Spearman and Kendall correlation; ;inear regression, Chi-square goodness-of-fit test and independence tests; sign test, Mann-Whitney U and Kruskal-Wallis H tests, probability tables (z, t, Chi-square, F, U); random number generator; Central Limit Theorem, Chi-square distribution.

MicrOsiris -- a comprehensive statistical and data management package for Windows, derived from the OSIRIS IV package developed at the University of Michigan. It was developed for serious survey analysis using moderate to large data sets. Main features: handles any size data set; has Excel data entry; imports/exports SPSS, SAS, and Stats datasets; reads ICPSR (OSIRIS) and UNESCO (IDAMS) datasets; data mining techniques for market analysis (SEARCH --very fast for large datasets); interactive decision tree for selecting appropriate tests; database maniuplation (dictionaries, sorting, merging, consistency checking, recoding, transforming) extensive statistics (univariate, staccerplot, cross-tabs, ANOVA/MANOVA, log-linear, correlation/regressionMCA, MNA, binary segmentation, cluster, factor, MINISSA, item analysis, survival analysis, internal consistency); online, web-enabled users manual; requires only 6MB RAM; uses 12MB disk, including manual. Fully-functional version is free; the authors would appreciate a small donation to support ongoing development and distribution.

Gnumeric -- a high-powered spreadsheet with better statistical features than Excel. Has 60 extra functions, basic support for financial derivatives (Black Scholes) and telecommunication engineering, advanced statistical analysis, extensive random number generation, linear and non-linear solvers, implicit intersection, implicit iteration, goal seek, and Monte Carlo simulation tools.

Statist -- a compact, portable program that provides most basic statistical capabilities: data manipulation (recoding, transforming, selecting), descriptive stats (including histograms, box&whisker plots), correlation & regression, and the common significance tests (chi-square, t-test, etc.). Written in C (source available); runs on Unix/Linux, Windows, Mac, among others.

Tanagra -- a free (open-source) data-mining package, which supports the standard "stream diagram" paradigm used by most data-mining systems. Contains components for Data source (tab-delimited text), Visualization (grid, scatterplots), Descriptive statistics (cross-tab, ANOVA, correlation), Instance selection (sampling, stratified), Feature selection and construction, Regression (multiple linear), Factorial analysis (principal components, multiple correspondence), Clustering (kMeans, SOM, LVQ, HAC), Supervised learning (logistic regr., k-NN, multi-layer perceptron, prototype-NN, ID3, discriminant analysis, naive Bayes, radial basis function), Meta-spv learning (instance Spv, arcing, boosting, bagging), Learning assessment (train-test, cross-validation), and Association (Agrawal a-priori). (French-language page here)

Dap -- a statistics and graphics package developed by Susan Bassein for Unix and Linux systems, with commonly-needed data management, analysis, and graphics (univariate statistics, correlations and regression, ANOVA, categorical data analysis, logistic regression, and nonparametric analyses). Provides some of the core functionality of SAS, and is able to read and run many (but not all) SAS program files. Dap is freely distributed under a GNU-style "copyleft".