General Packages: No package does everything, but these programs support a wide variety of statistical analyses.
Completely Free... can be freely downloaded and used in their fullyfunctional mode (no strings attached)  Free, but... "demonstration" or "student versions" of commercial packages; can be freely downloaded, but are usually restricted or limited in some way. 
OpenStat
 a general stats package for all Windows versions (including Win 7
and Win 8) and for Linux systems (under Wine), developed by Bill Miller
of Iowa State U, with a very broad range of data
manipulation and analysis capabilities and an SPSSlike user interface.
Bill also has provided an excellent User Manual as an Adobe Acrobat file. For some other interesting programs and documents, check out Bill's Web Site. Develve  stats package for fast and easy interpretation of experimental data in science and R&D in a technical environment. Everything is directly accessible and results are directly visible, with no hidden menus; e.g.: graphs are easily scrollable, and when clicked, a bigger version pops up. Results for group comparisons directly indicate the significance of the difference in average and variation, and if the sample size is sufficiently large. Has a basic mode for statistical testing, and a designofexperiments mode. SalStat2  a multiplatform, easytouse statistical system that provides data management (importing, editing, pivot tables), statistical calculations (descriptive summaries, probability functions, chisquare, ttests, 1way ANOVA, regression, correlation, nonparametric tests, SixSigma), and graphs (bar, line, scatter, area, histogram, box&whisker, stem, adaptive, ternary scatter, normal probability, quality control). 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...
OpenEpi Version 2.3  OpenEpi is a free, webbased, open source, operatingsystemindependent 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 popup 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 textbased graphics). Capabilities include: rearrange, transpose, tabulate and count data; random sample; basic descriptives; textplots for dot, boxandwhiskers, stemandleaf, histogram, scatterplot; find zvalues, confidence interval for means, ttests (one and two group, and paired; one and twoway ANOVA; Pearson, Spearman and Kendall correlation; ;inear regression, Chisquare goodnessoffit test and independence tests; sign test, MannWhitney U and KruskalWallis H tests, probability tables (z, t, Chisquare, F, U); random number generator; Central Limit Theorem, Chisquare 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, crosstabs, ANOVA/MANOVA, loglinear, correlation/regressionMCA, MNA, binary segmentation, cluster, factor, MINISSA, item analysis, survival analysis, internal consistency); online, webenabled users manual; requires only 6MB RAM; uses 12MB disk, including manual. Fullyfunctional version is free; the authors would appreciate a small donation to support ongoing development and distribution. Gnumeric  a highpowered 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 nonlinear 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 (chisquare, ttest, etc.). Written in C (source available); runs on Unix/Linux, Windows, Mac, among others. Tanagra  a free (opensource) datamining package, which supports the standard "stream diagram" paradigm used by most datamining systems. Contains components for Data source (tabdelimited text), Visualization (grid, scatterplots), Descriptive statistics (crosstab, 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., kNN, multilayer perceptron, prototypeNN, ID3, discriminant analysis, naive Bayes, radial basis function), Metaspv learning (instance Spv, arcing, boosting, bagging), Learning assessment (traintest, crossvalidation), and Association (Agrawal apriori). (Frenchlanguage page here) Dap  a statistics and graphics package developed by Susan Bassein for Unix and Linux systems, with commonlyneeded 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 GNUstyle "copyleft". PAST  an easytouse data analysis package aimed at paleontology including a large selection of common statistical, plotting and modelling functions: a spreadsheettype data entry form, graphing, curve fitting, significance tests (F, t, permutation t, Chisquared w. permutation test, KolmogorovSmirnov, MannWhitney, ShapiroWilk, Spearman's Rho and Kendall's Tau tests, correlation, covariance, contingency tables, oneway ANOVA, KruskalWallis test), diversity and similarity indices & profiles, abundance model fitting, multivariate statistics, time series analysis, geometrical analysis, parsimony analysis (cladistics), and biostratigraphy. AM  a free package for analyzing data from complex samples, especially largescale assessments, as well as nonassessment survey data. Has sophisticated stats, easy drag & drop interface, and integrated help system that explains the statistics as well as how to use the system. Can estimate models via marginal maximum likelihood (MML), which defines a probability distribution over the proficiency scale. Also analyzes "plausible values" used in programs like NAEP. Automatically provides appropriate standard errors for complex samples via Taylorseries approximation, jackknife & other replication techniques. Instat Plus  from the University of Reading, in the UK. (Not to be confused with Instat from GraphPad Software.) An interactive statistics package for Windows or DOS. WinIDAMS  from UNESCO  for numerical information processing and statistical analysis. Provides data manipulation and validation facilities classical and advanced statistical techniques, including interactive construction of multidimensional tables, graphical exploration of data (3D scattergram spinning, etc.), time series analysis, and a large number of multivariate techniques. SSP (Smith's Statistical Package)  a simple, userfriendly package for Mac and Windows that can enter/edit/transform/import/export data, calculate basic summaries, prepare charts, evaluate distribution function probabilities, perform simulations, compare means & proportions, do ANOVA's, Chi Square tests, simple & multiple regressions. Also, check out R and Ox, described in the Programming Languages section below. Dataplot  (Unix, Linux, PCDOS, Windows) for scientific visualization, statistical analysis, and nonlinear modeling. Has extensive mathematical and graphical capabilities. Closely integrated with the NIST/SEMATECH Engineering Statistics Handbook. WebStat  A Javabased statistical computing environment for the World Wide Web. Needs a browser, but can be downloaded and run offline. Regress+  A professional package (Macintosh only) for univariate mathematical modeling (equations and distributions). The most powerful software of its kind available anywhere, with stateoftheart functionality and userfriendliness. Too many features to even begin to list here. SISA  Simple Interactive Statistical Analysis for PC (DOS) from Daan Uitenbroek. An excellent collection of individual DOS modules for several statistical calculations, including some analyses not readily available elsewhere. Statistical Software by Paul W. Mielke Jr.  a large collection of executable DOS programs (and Fortran source). Includes: Matrix occupancy, exact gsample empirical coverage test, interactions of exact analyses, spectral decomposition analysis, exact mrbp (randomized block) analyses, exact multiresponse permutation procedure, Fisher's Exact for crossclassfication and goodnessoffit, Fisher's combined pvalues (meta analysis), largest part's proportion, PearsonZelterman, GreenwoodMoran and KendallSherman goodnessoffit, runs tests, multivariate Hotelling's test, leastabsolutedeviation regression, sequential permutation procedures, LAD regression, principal component analysis, matched pair permutation, r by c contingency tables, rway contingency tables, and JonkheereTerpstra. IRRISTAT  for data management and basic statistical analysis of experimental data (Windows). Primarily for analysis of agricultural field trials, but many features can be used for analysis of data from other sources. Includes: Data management with a spreadsheet , Text editor, Analysis of variance, Regression, Genotype x environment interaction analysis, Quantitative trait analysis, Single site analysis, Pattern analysis, Graphics, Utilities for randomization and layout, general factorial EMS, and orthogonal polynomial. 
SYSTAT
12  powerful statistical software ranging from the most
elementary descriptive statistics to very advanced statistical
methodology. Novices can work with its friendly and simple menudialog;
statisticallysavvy users can use its intuitive command language. Carry
out very comprehensive analysis of univariate and multivariate data
based on linear, general linear, and mixed linear models; carry out
different types of robust regression analysis when your data are not
suitable for conventional multiple regression analysis;compute partial
leastsquares regression;design experiments, carry out power analysis,
do probability calculations on many distributions and fit them to data;
perform matrix computations. Provides Time Series, Survival Analysis,
Response Surface Optimization, Spatial Statistics, Test Item Analysis,
Cluster Analysis, Classification and Regression Trees, Correspondence
Analysis, Multidimensional Scaling, Conjoint Analysis, Quality
Analysis, Path Analysis, etc. A 30day evaluation version is available
for free download.
Statlets  a 100% Pure Java statistics program. Should run on any platform (PC, Mac, Unix) that supports Java. The free Academic Version is limited to 100 cases by 10 variables. WINKS (Windows KWIKSTAT)  a fullfeatured, easytouse stats package with statistics (means, standard deviations, medians, etc.), histograms, ttests, correlation, chisquare, regression, nonparametrics, analysis of variance (ANOVA), probability, QC plots, cpk, graphs, life tables, time series, crosstabs, and more. Works on Windows XP (as well as Windows 2000, NT, 98, ME and 95.) Comes in Basic and Professional editions. Evaluation version available for download. StudyResult  (30day free trial) General statistics package for: paired & unpaired ttest, oneway ANOVA, Fisher's exact , McNemar's, Chi2, Chi^{2} homogeneity , life table & survival analysis, Wilcoxon ranksum & signedrank, sign test, bioequivalence testing, correlation & regression coefficient tests. Special features for interpreting summary data found in publications (pvalues & conf. intervals from summary statistics, converts pvalues to CI's & vice versa, what observed results are needed to get a significant result, estimates from publications needed for sample size calculations). Includes equivalence and noninferiority testing for most tests. STATGRAPHICS Plus v5.0 (for Windows)  over 250 statistical analyses: regression, probit, enhanced logistic, factor effects plots, automatic forecasting, matrix plots, outlier identification, general linear models (random and mixed), multiple regression with automatic CochraneOrcutt and BoxCox procedures, Levene's, Friedman's, Dixon's and Grubb's tests, DurbinWatson pvalues and 1variable bootstrap estimates, enhanced 3D charts. For Six Sigma work: gage linearity and accuracy analysis, multivari charts, life data regression for reliability analysis and accelerated lifetesting, longterm and shortterm capability assessment estimates. Two free downloads are available: fullfunction but limitedtime(30 days), and unlimitedtime but limitedfunction (no Save, no Print, not all analyses). NCSS2007 (Statistical Analysis System), PASS2008 (Power and Sample Size, and GESS (Gene Expression software for Microarrays) for Windows. Free 7day evaluation versions. MiniTab  a powerful, fullfeatured MS Windows package, with good coverage of industrial / quality control analyses. The free Version 12 Demo expires after 30 days. InStat (Instant Statistics), a fullfeatured statistics package from GraphPad Software. Demo version disables printing, saving and exporting capabilities. Demo available for Windows only; commercial version available for Windows and Mac. Prism  from GraphPad Software. Performs basic biostatistics, fits curves and creates publication quality scientific graphs in one complete package (Mac and Windows). Windows demo is fullyfunctional for 30 days, then disables printing, saving and exporting; Mac demo always disables these functions. CoStat 6.2  an easytouse program for data manipulation and statistical analysis, from CoHort Software. Use a spreadsheet with any number of columns and rows of data: floating point, integer, date, time, degrees, text, etc. Import ASCII, Excel, MatLab, S+, SAS, Genstat, Fortran, and others. Has ANOVA, multiple comparisons of means, correlation, descriptive statistics, analysis of frequency data, miscellaneous tests of hypotheses, nonparametric tests, regression (curve fitting), statistical tables, and utilities. Has an autorecorder and macro programming language. Callable from the command line, batch files, shell scripts, pipes, and other programs; can be used as the statistics engine for web applications. Free timelimited demo available.

Subset Packages: Each of these programs deals with a specific area of statistics (such as power analysis or mulitvariate analysis), or carries out a specific test or computation.
Completely Free... can be freely downloaded and used in their fullyfunctional mode (no strings attached)  Free, but... "demonstration" or "student versions" of commercial packages; can be freely downloaded, but are usually restricted or limited in some way. 
PS
 a wellimplemented Windows program for power
and sample size calculations from Vanderbilt Univ Med Ctr.
Handles dichotomous, continuous,or survival response measures, which
are analyzed by chisquare or Fisher Exact tests, Student t tests, and
logranks tests, respectively. The alternative hypothesis may be
specified either in terms of differing response rates, means, or
survival times, or in terms of relative risks or odds ratios. Studies
with dichotomous or continuous outcomes may involve either a matched or
independent study design. The latest version also handles
MantelHaenszel tests. Can determine sample size for
a specified power, power for a specified sample size,
or the specific alternative hypotheses that can be detected with a
given power and sample size. Produces graphs of relationships between
power, sample size and detectable alternative hypotheses (with any two
of these variables on x & y, and the third variable generating
a family of curves on a single graph). Linear or logarithmic
axes may be specified. Can print professionalquality power charts. The
latest version also provides a concise and precise verbal description
of each power analysis, which you can copy and paste into the
Power/SampleSize section of your proposal or protocol.
G*Power 3  a very general Power Analysis program for Windows and Macintosh. Performs exact analysis for 6 types of correlation tests, 3 types of bivariate regression tests, 1group and 2group comparison of means tests (parametric and nonparametric), 4 types of multiple regression tests, logistic regression, poisson regression, ordinary and repeatedmeasures ANOVAs, ANCOVAs, MANOVAs, multivariate T2 and MANOVAs, 8 types of tests of proportions (McNemar, Fisher, etc.), 1group and 2group variance tests, and completely generic tests involving the binomial, normal, t, chisquare, and F distributions. Computes power, sample sizes, alpha, beta, and alpha/beta ratios. Has a comprehensive webbased tutorial and reference manual. Factor  a comprehensive factor analysis program. Provides univariate and multivariate descriptive statistics of input variables (mean, variance, skewness, kurtosis), Var charts for ordinal variables, dispersion matrices (user defined , covariance, pearson correlation, polychoric correlation matrix with optional Ridge estimates). Uses MAP, PA (Parallel Analysis), and PA  MBS (with marginally bootstrapped samples) to determine the number of factors/components to be retained. Performs the following factor and component analyses: PCA, ULS (with Heywood correction), EML, MRFA, SchmidLeiman secondorder solution, and Factor scores. Rotation methods: Quartimax, ,Varimax , Weighted Varimax, Orthomin , Direct Oblimin, Weighted Oblimin, Promax, Promaj , Promin, and Simplimax. Indices used in the analysis: dispersion matrix tests (determinant, Bartlett's, KaiserMeyerOlkin), goodness of fit: ChiSquare ,nonnormed fit index, comparative fit index, goodness of fit index, adjusted GFI, RMS error of approx, and estimated noncentrality parameter (NCP), reliabilities of rotated components , simplicity indices: Bentler’s, and loading simplicity index. Provides mean, variance and histogram of fitted and standardized residuals, and automatic detection of large standardized residuals. KEYFINDER  a menudriven interactive program for generating, randomizing and tabulating blocked and/or fractionalreplicate factorial designs in completely general situations. It can generate blocked and/or fractionalreplicate designs with userspecified confounding and aliasing properties. KEYFINDER runs on all versions of Windows. You can download the Version 3.3 Overview document, in PDF format, here. To obtain a free copy of the program and manual, send an email to the author: Peter.Zemroch@shell.com Weka  a collection of machine learning algorithms for data mining tasks, implemented in Java. Can be executed from a commandline environment, or from a graphical interface, or can either be called from your own Java code. Weka contains tools for data preprocessing, classification, regression, clustering, association rules, and visualization, and is wellsuited for developing new machine learning schemes. StatCalc  a PC calculator that computes table values and other statistics for 34 probability distributions. Also includes some nonparametric table values, tolerance factors, and bivariate normal distribution. A help file is provided for each distribution. Scientific Calculator  ScienCalc program contains highperformance arithmetic, trigonometric, hyperbolic and transcendental calculation routines. All the function routines therein map directly to Intel 80387 FPU floating point machine instructions. Distributions  Windows program allows for the analysis of discrete single dimension distributions. The program is based on various manipulations of the poisson, binomial and hypergeometric distribution. Available are the probability of an observed number of cases given a certain null hypothesis, the calculation of exact poisson, binomial or hypergeometric confidence intervals, the exact and approximate size of a population using catchrecatch methodologies, the full analysis of a Poisson distributed rate ratio, Fieller analysis, and two versions of the negative binomial distribution can be used in various ways. Beside the exact procedures there are also various approximate procedures available. From the Downloads section of the QuantitativeSkills web site. Multinomial  This Windows program is the exact solution to the Chisquare Goodness of fit test of testing for a difference between an observed and an expected distribution in a onedimensional array. For example, the test can be used to compare the distribution of diseases in a certain locality with an expected distribution on the basis of national or international experiences using an ICD classification. In a twocategory array the multinomial test provides a twosided solution for the Binomial test. For example, Multinomial {10 20 0.20 0.80} gives the twosided probability (0.105) for the single sided Binomial {0.20 10 30} probability (0.061). The multinomial allows you to work with empty '0' observation cells although you must have an expectation about a cell. From the Downloads section of the QuantitativeSkills web site. Tables  a Windows program for the analysis of tables with up to 2*7 and 3*3 cells. The program allows for exact and approximate statistics to be calculated for traditional, ordinal and agreement tables. Fisher exact, Number Needed to Treat, Proportional Reduction in Error Statistics, Normal Approximations, Four different Chisquares, Gamma, Oddsratio, ttests and Kappa are among the many statistical procedures available. From the Downloads section of the QuantitativeSkills web site. MorePower  another wellimplemented power/samplesize calculator for any ANOVA design, for 1 and 2sample ttests, and for 1 and 2sample binomial testing (sign test, chisquare test). EqPlot  Equation graph plotter program plots 2D graphs from equations. The application comprises algebraic, trigonometric, hyperbolic and transcendental functions. BlockTreat  a Java program that implements a very general Monte Carlo procedure that performs nonparametric tests (based on random permutations, not ranks) for block and treatment tests, tests with matching, ksample tests, and tests for independence between any two random variables. Designs may be incomplete and unbalanced, or even have supernumerary entries. The tests are "exact", in the MonteCarlo sense  they can be made as accurate as desired by specifying enough random shuffles. PCP (Pattern Classification Program)  a machinelearning program for supervised classification of patterns (vectors of measurements). PCP implements: Fisher's linear discriminant, dimensionality reduction using SVD, PCA, feature subset selection, Bayes error estimation, parametric classifiers (linear and quadratic), LS (pseudoinverse) linear discriminant, kNearest Neighbor, neural networks (MultiLayer Perceptron), SVM, model selection for SVM, crossvalidation, and bagging (committee) classification. Supports interactive (keyboarddriven menus) and batch processing. PEPI  a collection of 43 small DOS / Windows programs that perform a large assortment of statistical tests. They can be downloaded individually, or as a single ZIP file. (A new Windows version is being developed; the test version can be downloaded here.) They were written to accompany the book Computer Programs for Epidemiologic Analyses: PEPI v. 4.0, by Abramson and Gahlinger, which is available for purchase. A freelyaccessible article describing the new features of WinPEPI can be accessed here. The programs include: pvalue adjustments for multiple significance tests; Attributable and Prevented Fractions: CaseControl Studies; Analysis of 2 x 2 Tables; Chisquare Tests of Association; Combining Measures of Association or Probabilities; Confidence Intervals; Aids to Use of Pearson's Correlation Coefficients; ifference Between Rates, Proportions or Means; Direct Standardization; Exact Test for a 2 x K Table; Tests for Goodness of Fit ; Fitting of Poisson and Binomial Distributions; Appraisal of Frequency Distribution ; Indirect Standardization; Agreement Between Categorical Ratings; Life Table Analysis; Logistic Regression Analysis (Unconditional and Conditional); WilcoxonMannWhitney Test and Related Procedures ; Extended MantelHaenszel Procedure: Trend Analysis; Multiple Matched Controls; Correcting for Misclassification in 2 x 2 Tables; Analysis of Paired Samples ; Poisson Probability: Observed vs Expected Events; Poisson Regression Analysis; Power of a Test Comparing Two Proportions or Means; Probability and Inverse Probability Values: Z, t, Chi Square, F; Procedures using Random Numbers; Association Between OrdinalScale Variables; Comparison of Two Rates or Proportions; Comparison of PersonTime Incidence Rates; ower and Sample Size for Regression and Correlation Analyses; Comparison of Several Related Samples; Sample Size for Estimation of Proportion, Rate, or Mean; Sample Sizes for Comparison of Two Samples ; Internal Consistency of a Scale; Screening and Diagnostic Tests ; Seasonal Variation ; Smoothing of Curves and Median Polish Procedure; KaplanMeier Life Table Analysis, Logrank and Logitrank Tests; Calculation of Elapsed Time; Trend Analysis and Multiple Comparisons, and two special calculators: WHATIS and WHATS. TETRAD (from the TETRAD Project at CMU)  a free program for creating, simulating data from, estimating, testing, predicting with, and searching for causal/statistical models of categorical (or ordinal) data and to linear models ("structural equation models') with a Normal probability distribution, and to a very limited class of time series models. Provides sophisticated methods in a friendly interface. It performs many of the functions in commercial programs such as Netica, Hugin, LISREL, EQS and other programs, and many discovery functions these commercial programs do not perform. TETRAD is limited to models The TETRAD programs describe causal models in three distinct parts or stages: a picture, representing a directed graph specifying hypothetical causal relations among the variables; a specification of the family of probability distributions and kinds of parameters associated with the graphical model; and a specification of the numerical values of those parameters. EasySample  a tool for statistical sampling. Supports several types of attribute and variable sampling and includes a random number generator and standard deviation calculator. Has a consistent, easytouse interface. Results may be saved or read in CSV (spreadsheet compatible) or XML (Internet compatible) file formats or printed. EpiData  a comprehensive yet simple tool for documented data entry. Overall frequency tables (codebook) and listing of data included, but no statistical analysis tools. Calculate sample size required for a given confidence interval, or confidence interval for a given sample size. Can handle finite populations. Online calculator also available. Grocer  a free econometrics toolbox that runs under Scilab. It contains: most standard econometric capabilities: ordinary least squares, autocorelated models, instrumental variables, non linear least squares, limited dependent variables, robust methods, specification tests (multicolinearity, autocorelation, heteroskedasticity, normality, predictive failure,...), simultaneous equations methods (SUR, two and three stage least squares,...), VAR, VECM, VARMA and GARCH estimation, the Kalman filter and time varying parameters estimation, unit root tests (ADF, KPSS,...) and cointegration methods (CADF, Johansen,...), HP, BaxterKing and ChristianoFitzgerald filters. It also contains some rare and useful features: a pcgets device that performs automatic general to specific estimations, and a contributions device, that provides contributions of exogenous variables to an endogenous one for any dynamic equation. Has a rough interface with Excel and unlike Gauss or Matlab, it deals with true timeseries objects. Biomapper  a kit of GIS and statistical tools designed to build habitat suitability (HS) models and maps for any kind of animal or plant. Deals with: preparing ecogeographical maps for use as input for ENFA (e.g. computing frequency of occurrence map, standardisation, masking, etc.); Exploring and comparing them by mean of descriptive statistics (distribution analysis, etc.); Computing the Ecological Niche Factor Analysis and exploring its output; and Computing and evaluating a Habitat Suitability map ROC Curves  a set of downloadable programs and Excel spreadsheets to calculate and graph various kinds of ROC (Receiver Operator Characteristic) curves. BKD: Bayesian Knowledge Discoverer  a computer program able to learn Bayesian Belief Networks from (possibly incomplete) databases. Based on a new estimation method called Bound and Collapse. Developed within the Bayesian Knowledge Discovery project. See also the commercial product, called Bayesware Discoverer, available free for noncommercial use. RoC: The Robust Bayesian Classifier  a computer program able to perform supervised Bayesian classification from incomplete databases, with no assumption about the pattern of missing data. Based on a new estimation method called Robust Bayesian Estimator. Developed within the Bayesian Knowledge Discovery project. DQOPRO  a samplesize calculator for MS Windows that performs three types of calculations:
Binomial Probability Program (BPP) is a menu driven program which performs a variety of functions related to the success/ failure situation. Given the probability of occurrence for a specific event, this program calculates the probability that EXACTLY, NO MORE THAN, or AT LEAST a certain number of events occur in a given number of trials for all possible outcomes, and will generate plots for each of these. The program allows the user to repeatedly combine probabilities in series or in parallel, and at any time will show a trail of the calculations which led to the current probability value. Other program capabilities are the calculation of probabilities from input data, Gaussian approximation, and the generation of a mean time between failure (MTBF) table for various levels of confidence. Up to 2200 trials may be run, limited by IBM PC BASIC memory utilization. It is assumed that the user is familiar with the theory behind binomial probability distribution. ADE4  multivariate analysis and graphical display software package for Mac andWin 95/NT. Includes component analysis and correspondence analysis, spatial data analysis methods (analogous to Moran and Geary indices), discriminant analysis and within/between groups analyses, many linear regression methods including lowess and polynomial regression, multiple and PLS (partial least squares) regression and orthogonal (principal component) regression, projection methods like principal component analysis on instrumental variables, canonical correspondence analysis and many other variants, coinertia analysis and the RLQ method, and several threeway table (ktable) analysis methods. Graphical displays include an automatic collection of elementary graphics corresponding to groups of rows or to columns in the data table, automatic ktable graphics and geographical mapping options, searching, zooming, selection of points, and display of data values on factor maps. Simple and homogeneous user interface.
Weibull Trend Toolkit  Fits a Weibull distribution function (like a normal distribution, but more flexible) to a set of data points by matching the skewness of the data. (Windows) TURNER  Macintosh software for interactivly analysing multidimensional discrete data. Uses interactive paradigms from exploratory graphical data analysis to the concise treatment of categorical data, typically arranged in two or multiway contingency tables. Including standard features for categorical data like Pearson's chisquared test and loglinear models it offers the whole goodnessoffit family of power divergence statistics and the Nvalue. Interactive contingency tables provide the user with the facility of easily switching between all twodimensional views of multivariate data. All displays dealing with the same data set are fully linked and may be interacted with directly. BUGS  Bayesian inference Using Gibbs Sampling. Software for the Bayesian analysis of complex statistical models using Markov chain Monte Carlo (MCMC) methods. Commandline interface versions available for major computer platform; a Windows version, WinBUGS, supports a graphical user interface, online monitoring and convergence diagnostics. MSBNx  a componentbased Windows application for creating, assessing, and evaluating Bayesian Networks, created at Microsoft Research. Includes complete help files and sample networks. Bayesian Networks are encoded in an XML file format. QUEST (Quick, Unbiased and Efficient Statistical Tree), and CRUISE (Classification Rule with Unbiased Interaction Selection and Estimation. Two statistical decision tree algorithms for classification and data mining, by WeiYin Loh and YuShan Shih. AMELIA  A program for substituting reasonable values for missing data (called "imputation") A collection of MSDOS program from the Downloads section of the QuantitativeSkills web site:

Data
Preparator
 handles the "preprocessing" chores of getting a data file ready for
analysis... data cleaning, discretization, numeration, scaling,
attribute selection,
missing values, outliers, statistics, visualization, balancing,
sampling, row selection, and several other tasks, with a userfriendly
graphical interface. It's written in Java, and runs on Windows, Mac
OS/X, and Linux. The free demo has all features enabled, and will
handle up to 200 cases.
StatCalc
(30day free trial download)  a handy desktop tool and instructional
aid that transforms from a standard calculator to a collection of
modules that calculate statistics, graph distributions, and provide
statistical help with definitions, formulas, and interpretation.
(Windows) WinSPC (30day free trial) statistical process control software to:
The Unscrambler  multivariate data analysis software for exploratory statistics, regression analysis, classification, prediction, principal components analysis (PCA), partial least squares regression (PLSR) analysis and threeway PLS regression and experimental design. Free 30day evaluation copy available. ADDPLAN  software for sample size calculation and adaptive monitoring of clinical trials. Handles traditional single fixed sample designs, survival analyses, proportions, means, noninferiority, flexible (adaptive) designs, groupsequential designs, ?spending function designs, simultaneous control of Type I & II error, adaptive sample sze recalculation, recursive designs based on conditional Type I error, interim monitoring & analysis, classical stopping boundaries, repeated and endoftrial conf. inter's and pvalues, and a powerful simulation tool. Free 30day limitedfunction trial version available for download. Statistics Problem Solver  tutoring software that not only solves statistical problems, but also generates stepbystep solutions in order to help students understand how to solve statistical problems. Includes: Histograms, Binomial, Poisson, Exponential, Continuous, Group Comparison and Test of Significance. Two other similar tutorial programs are available from the same company: A&G Grapher  for plotting any 2D or 3D equation typed into the program. Graphs can be customized in color, scale, resolution, etc., and can be exported or copiedandpasted into other application. Also calculates slope, area under the curve, tracing and matrix transformation. Calculus Problem Solver  differentiates any arbitrary equation and outputs the result, providing detailed stepbystep solutions in a tutoriallike format. Can also initiate an interactive quiz in which you can solve differentiation while the computer corrects your solutions. Power and Precision  (30day free trial download) An "industrial strength" program for calculating power, sample size, and attainable precision for: ttests and ztests (1group, 2group, paired, unpaired), Proportions (1group, 2group Chi Square or Fisher Exact, McNemar, KxC, Sign test), Correlations (1group and 2group), ANOVA / ANCOVA (1, 2, or 3way), Multiple hierarchical linear regression (covariates / main effects, interactions, dummycoded variables, polynomial), R^{2} increments, sequential sets), Logistic regression (1 or 2 continuous variables, 5level categorical), Survival analysis (accrual options , constant or variable hazard, attrition), Equivalence tests (proportions or means). StudySize (free demo subset and 30day trial versions)  for power / precision / sample size calculations, hypothesis testing, point estimation and confidence interval calculations. Includes equivalence and noninferiority testing for most tests, Monte Carlo simulation for small samples; group sequential interim analyses . Tests: Wilcoxon, MannWhitney, Sign; Student t, 1way ANOVA, Fisher's exact, McNemar's,Chi2, Life table, Logrank,Bioequivalence, Correlation and Regression coefficients. Point estimates & confidence intervals for means, medians, SDs, location & scale params in normal, lognormal, exponential, binomial, hypergeometric, Poisson distributions, and more. DesignEase and DesignExpert  two programs from StatEase that specialize in the design of experiments. Fullfunction 45day evaluation copies of both programs are available for download. AGREE  to measure agreement of nominal data, where two or more judges classify objects into nominal scale categories. Bayesware Discoverer  a computer program able to learn Bayesian Belief Networks from (possibly incomplete) databases. Based on a new estimation method called Bound and Collapse. This is a commercial product, available free for educational and other noncommercial use. See also the freeware product: BKD: Bayesian Knowledge Discoverer. ZeroRejects  Implements the "Six Sigma" statistical process control methodology developed by Motorola. The alpha and beta version are freely downloadable. (Win 95/98/NT). Prognosis  for analysis of timeseries data. Uuses artificial intelligence and powerful statistical methodology to achieve high forecasting accuracy. Easy to use; does not require any background in statistics or time series analysis. Free evaluation copy available for download.

Completely Free... can be freely downloaded and used in their fullyfunctional mode (no strings attached)  Free, but... "demonstration" or "student versions" of commercial packages; can be freely downloaded, but are usually restricted or limited in some way. 
EasyReg
(Easy Regression Analysis), by Herman J. Bierens. Incredibly powerful
and multifeatured program for data manipulation and analysis. Designed
for econometrics, but useful in many other disciplines as
well. For Win 98/98/NT4. Also see RegressIt in the Excel Spreadsheets and Addins section. Compumine Rule Discovery System  easy to use data mining software for developing highquality rule based prediction models, such as classification and regression trees, rule sets and ensemble models. This program is licensed under the P3 license model wich means that it is free to use forever for developing rulebased predictive models, and can be freely downloaded here. gretl  a crossplatform (Linux, Windows, Mac, etc.) package for econometric analysis. Has an intuitive interface (English, French, Italian & Spanish). Supports a wide variety of leastsquares based estimators, including twostage & nonlinear least squares, augmented DickeyFuller test, Chow test for structural stability, Vector Autoregressions, ARMA estimation. Creates output modelss as LaTeX files, in tabular or equation format. Has an integrated scripting language: enter commands either via the gui or via script, command loop structure for Monte Carlo simulations and iterative estimation procedures, GUI controller for finetuning Gnuplot graphs, Link to GNU R for further data analysis. Reads own format XML data files, Comma Separated Values files, Excel and Gnumeric worksheets, BOX1 files, own format binary databases (allowing mixed data frequencies and series lengths) and RATS 4 databases. Includes a sample US macro database. See also the gretl data page. mle  Maximum Likelihood Estimation  a simple programming language for building and estimating parameters of likelihood models. Originally designed for survival models, but the language has evolved into a generalpurpose tool for building and estimating general likelihood models. Available for Windows and Linux; also provides User Manual, Reference Manual, and Quick Reference Card. WinSAAM  Windows implementation of SAAM (System Analysis and Modeling Software). Lets you create mathematical models, design and simulate experiments, and analyze data. Models can contain differential equations, which will be numerically integrated and fit to data. Graphic and tabular output is provided. Boomer  Nonlinear Regression Program for Analysis of Pharmacokinetic and Pharmacodynamic Data. Includes normal fitting, Bayesian estimation, or simulationonly, with integrated or differential equation models. Allows selection of weighting schemes and methods for numerical integration. Free downloads for Macintosh and Windows; online manual, tutorial, sample data sets. DEMETRA  userfriendly interface to TRAMO/SEATS and X12ARIMA . JoinPoint Regression Program (from the National Cancer Institute)  for the analysis of trends using joinpoint models (where several different lines are connected together at the "joinpoints."). Takes trend data (e.g cancer rates) and fits the simplest joinpoint model that the data allow, using a Monte Carlo Permutation method. Models may incorporate estimated variation for each point (e.g. when the responses are age adjusted rates) or use a Poisson model of variation. In addition, the models may also be linear on the log of the response (e.g. for calculating annual percentage rate change). The software also allows viewing one graph for each joinpoint model, from the model with the minimum number of joinpoints to the model with maximum number of joinpoints. 
CurveExpert
 comprehensive curve fitting system for Windows. Handles linear
regression models, nonlinear regression models, interpolation, or
splines. Over 30 models builtin; custom userdefined regression
models. Fullfeatured graphing capability. Supports an automated
process that compares your data to each model to choose the best curve.
30day evaluation of shareware package.
DTREG generates classification and regression decision trees. It uses Vfold crossvalication with pruning to generate the optimal size tree, and it uses surrogate splitters to handle missing data. A free demonstration copy is available for download. NLREG performs general nonlinear regression. NLREG will fit a general function, whose form you specify, to a set of data values. A free demonstration copy is available for download. Partitionator  a fast recursive partitioning engine that uses a learning set to generate rules by which a dependent variable can be predicted, by optimally splitting continuous predictors. Free 30day evaluation. NeuroSolutions  applies neural network technology to many situations, including regression. Free evaluation version does everything except print or save networks. LOCFIT  a software system for fitting curves and surfaces to data, using the local regression and likelihood methods. (from Bell Labs) Runs on various platforms under R or S statistical systems; also available as a standalong package for Win95/98/NT. Origin  technical graphics and data analysis software for Windows. Includes 3D and contour plotting, FFT filtering; works closely with Excel. 30 evaluation. CART  Salford Systems flagship decisiontree software, combines an easytouse GUI with advanced features for data mining, data preprocessing and predictive modeling. 
Biostatistics and Epidemiology:
Completely Free... can be freely downloaded and used in their fullyfunctional mode (no strings attached)  Free, but... "demonstration" or "student versions" of commercial packages; can be freely downloaded, but are usually restricted or limited in some way. 
OpenEpi
Version 2.2.1  OpenEpi is a free, webbased, open source,
operatingsystemindependent series of programs for use in public
health and medicine, providing a number of epidemiologic and
statistical tools. It is written in JavaScript and HTML and operates
similar to a calculator. OpenEpi can be thought of as an important
companion to Epi Info, EpiData, SAS, SPSS, and Stata.
M.D. Anderson Statistical Software Library A large collection of free statistical software (almost 70 programs!) from the Biostatistics and Applied Mathematics department of the M.D. Anderson Cancer Center. Software is distributed in the form of program source files and/or selfextracting archives of executable programs for Windows, Mac, Unix/Linux environments. Lifetables  Windows program for Mortality Analysis for Demography and Epidemiology. The program will calculate the life expectancy, including all intermediary statistics, variance an confidence interval for the life expectancy, Potential Gains in Life Expectancy (PGLE), Years of Potential Life Lost (YPLL) and Lifetime Years of Potential Life Lost (LYPLL). YPLL can be calculated adjusted for competing causes of mortality and both YPLL and LYPL can also be discounted. Two populations can be compared using direct and indirect standardization, the SMR and CMF and by comparing two lifetables. Confidence intervals and statistical test are provided. There is an extensive helpfile in which everything is explained. From the Downloads section of the QuantitativeSkills web site. Sample Size for Microarray Experiments  compute how many samples needed for a microarray experiment to find genes that are differentially expressed between two kinds of samples (e.g.: cancer vs. normal tissue), by performing separate genebygene ttests. You specify how many genes you're looking at, how many false positives you are willing to accept, how large a difference you want to be able to detect (as the fold difference between the two kinds of samples), the power of the test (% of differentially expressed genes likely to be detected by the experiment), and an estimate of the logarithmic SD of the gene intensities. MIX (Metaanalysis with Interactive eXplanations)  a statistical addin for Excel 2000 or later (Windows only). Ideal for learning metaanalysis (reproduces the data, calculations, and graphs of virtually all data sets from the most authoritative metaanalysis books, and lets you analyze your own data "by the book"). Handles datasets with dichotomous & continuous outcomes; calculates Risk Diff, RR, OR, Mean Diff, Hedges's g, Cohen's d; performs standard & cumulative metaanalysis with CI ,z & p; fixed and random effects modeling; Cochran's Q with pvalue; Higgins's I2 and H with CI; and publication bias tests: Rank correlation (taub) test with z & p, Egger's and Macaskill's regression tests with CI, and TrimandFill. Generates numerous plots: tandard and cumulative forest, pvalue function, four funnel types, several funnel regression types, exclusion sensitivity, Galbraith, L'Abbe, Baujat, modeling sensitivity, and TrimandFill. EWOC  Escalation With Overdose Control  a Bayesian method for selecting dose levels in Phase I Clinical Trials while controlling the probability of exceeding the maximum tolerated dose. This is a standalone Windows (95 through XP) program that receives information about doselimiting toxicities (DLTs) observed at some starting dose, and calculates the doses to be administered next. DLT information obtained at each dosing level guides the calculation of the next dose level. (For some strange reason, the EWOC download web site does not work properly with the FireFox web browser; but it does work with MS Internet Explorer.) STPLAN  Performs power, sample size, and related calculations needed to plan studies. Covers a wide variety of situations, including studies whose outcomes involve the Binomial, Poisson, Normal, and lognormal distributions, or are survival times or correlation coefficients. Available for MSDOS and Mac; also as Fortran and C source code. Epi InfoVersion 3.5.1  Public domain statistical software for epidemiology developed by Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia (USA). Epi Info has been in existence for over 20 years and is currently available for Microsoft Windows. The program allows for data entry and analysis. Within the analysis module, analytic routines include ttests, ANOVA, nonparametric statistics, cross tabulations and stratification with estimates of odds ratios, risk ratios, and risk differences, logistic regression (conditional and unconditional), survival analysis (Kaplan Meier and Cox proportional hazard), and analysis of complex survey data. The software is in the public domain, free, and can be downloaded from http://www.cdc.gov/epiinfo. Limited support is available. PEPI  a collection of 43 small DOS / Windows programs that perform a large assortment of statistical tests. They can be downloaded individually, or as a single ZIP file. Free Public Health & Epidemiology Software  written by Mark Myatt)and others:
PAMCOMP (Personyears And Mortality COMputation Program)  a free Windows 95/98/NT application for calculating personyears and standardised mortality ratios (SMRs). The calculation of personyears allows flexible stratification by sex, and selfdefined and unrestricted calendar periods and age groups, and can lag personyears to account for latency periods.The SMR computation includes calculation of 90%, 95%, and 99% confidence intervals. Has filters for ASCII, dBase, Excel, Access, Paradox to import cohort and reference data and to export distributions of personyears and deaths. ARIMA  a seasonal adjustment program for PC and Unix, developed by the Census Bureau. DEMETRA  (Win 9x/NT) a userfriendly interface to the seasonal adjustment methods TRAMO/SEATS and X12ARIMA . Developed by Eurostat to facilitate the application of these modern time series techniques to largescale sets of time series and in the explicit consideration of the needs of production units in statistical institutes. Client/server architecture can access various kinds of databases and files. Contains two main modules: seasonal adjustment and trend estimation with an automated procedure (e.g. for unexperienced users or for largescale sets of time series), and with a userfriendly procedure for detailed analysis of single time series. Metaanalysis 5.3  Free DOS statistics software for metaanalysis. Probably still the most frequently used metaanalysis software in the world. Can select the analysis of exact p values or effect sizes (d or r, with a cluster size option). Can plot a stemandleaf display of correlation coefficients. A utility menu is provided that allows various transformations and preliminary computations that are typically required before the final metaanalysis can be performed. EasyMA  a free userfriendly MSDOS program for the metaanalysis of clinical trials results. Developed to help physicians and medical researchers to synthesize evidence in clinical or therapeutic research. EPIMETA (from CDC)  a DOSbased metaanalysis program that features a Windowslike interface which makes data entry, file manipulation, and subgroup analysis easy. Life Table  available in Lotus and Excel formats. ABSRISK  a program (MSDOS) for estimating absolute risks from relative risks. Uses agespecific mortality and morbidity data to convert relative risk estimates into absolute risk estimates. That is, it estimates the probability that a patient will suffer a specific morbid or mortal outcome in a given time interval. The user first specifies a data file that contains the needed mortality and morbidity data for the disease of interest. She then gives her patient's age and relative risk, and the time interval over which the risk estimate is to be derived. The program derives this risk, which is given both interactively and in a log file. Biodiversity Research Software  Five software packages, with documentation:

HICAST  a PCbased program for rapid entry of clinical and laboratory parameters needed for the calculation of ten internationally applied scoring systems used on the an Intensive Care Unit. Allows sharing of relvant data, so multiple enrties of the same data are not necessary. 
Surveys, Testing, and Measurement:
Completely Free... can be freely downloaded and used in their fullyfunctional mode (no strings attached)  Free, but... "demonstration" or "student versions" of commercial packages; can be freely downloaded, but are usually restricted or limited in some way. 
CCOUNT
 a package for market research data cleaning, manipulation, cross
tabulation and data analysis. Similar to, and uses the same
syntax as, SPSSMR "Quantum", a well known commercial package for
processing market research data. Available for Windows, Linux, and
SunOS. C++ source code also available, under the GNU General Public
Licerse.
ProtoGenie  a free extensible webbased environment for research design and data collection for surveys, experiments, clinical trials, time series, cognitive and vision research, and methods courses. Lets you specify groups and define measurement and treatment events and their sequencing. The goal is to let users move smoothly from research design and data collection to interim and final statistical analysis. GGUM2004 (Item Response Theory Models for Unfolding)  a Windowsbased program that estimates parameters in the generalized graded unfolding model (GGUM; Roberts, Donoghue, & Laughlin, 2000). Has a userfriendly interface to prepare command files, run the core estimation program, and display results. Allows different questionnaire items to have varying numbers of response categories (useful when sparse responses require recoding into fewer response categories. Handles sporadically missing responses. Provides item fit statistics and diagnostic graphics of performance. Rasch Measurement Software  deals with the various nuances of constructing optimal rating scales from a number of (usually) dichotomous measurements, such as responses to questions in a survey or test. Several free student/demo software packages are available. These may be freely downloaded, used, and distributed, and they do not expire. They are:
QMethod  a statistical program for analyzing data from the QSort Technique. Enter data (QSorts) the way they are collected, i.e. as 'piles' of statement numbers. It computes intercorrelations among QSorts, which are then factoranalysed with the Centroid (or, alternatively, PCA) method. Resulting factors can be rotated either analytically (Varimax), or judgmentally with the help of twodimensional plots. Finally, after selecting the relevant factors and 'flagging' the entries that define the factors, the analysis step produces an extensive report with a variety of tables on factor loadings, statement factor scores, discriminating statements for each of the factors as well as consensus statements across factors, etc. AnSWR  Analysis Software for Wordbased Records  a free software system from the C.D.C. for coordinating and conducting largescale, teambased analysis projects that integrate qualitative and quantitative techniques (for Windows). eztext  a software program from the C.D.C. developed to assist researchers create, manage, and analyze semistructured qualitative databases. CSPro (Census and Survey Processing System)  a publicdomain software package for entering, tabulating and mapping census and survey data. IMPS (Integrated Microcomputer Processing System)  performs the major tasks in survey and census data processing: data entry, data editing, tabulation, data dissemination, statistical analysis and data capture control. (from CDC) WebQ  a set of HTML files for performing QSorts online and collecting the data for subsequent analysis. Stats  Windows program for several commonlyneeded statistical functions for marketing researchers: random numbers;sample sizes needed for surveys; mean, standard deviation, standard error and range for keyboardentered data; standard error of a proportion; significance testing between two percentages from independent samples; significance between two percentages from dependent samples; significance testing between two averages from independent samples; contingency table analysis (i.e., ChiSquare) SABRE  for the statistical analysis of multiprocess random effect response data. Responses can be binary, ordinal, count and linear recurrent events; response sequences can be of different types. Such multiprocess data is common in many research areas, e.g. the analysis of work and life histories. Sabre has been used intensively on many longitudinal datasets surveys either with recurrent information collected over time or with a clustered sampling scheme. POSDEM  Uses simulation techniques to analyze and compare alternate sampling strategies for surveys. Performs power / sample size / precision analyses for different sampling methods: systematic, stratified, random, etc. Windows versions available in Spanish and English. WISCIII Profile Calculator for Macintosh and Windows  uses generalized distance method to determine if the subtest profile of a single case is multivariately unusual or common in comparison to subtest clusters found in the WISCIII standardization sample. (Mac, 360K; Win anticipated in September) DEMETRA  userfriendly interface to TRAMO/SEATS and X12ARIMA . Sociological Insights  displays statistical information in an easytouse format, designed for teaching quantitative sociological reasoning. It uses aggregate data from the 50 U.S. states to teach the principles of distribution, correlation, and regression. It uses questionnaire data from the 2000 and 1994 General Social Surveys to teach distribution and crosstabulation. The States module has 289 variables in all. The Survey module displays 249 variables from the 2000 GSS, plus (as a separate data set) 113 variables from the 1994 GSS. 
Form
Artist  lets you design and create online forms for data
collection via the Web. Forms and surveys run on any web server
(Microsoft, Unix, Linux ), and work with all browsers (no plugins
required. WYSIWYG interface gives complete control over the appearance
of forms (any shape, size, number of pages, color scheme). Create
multipage forms on the same web page without reloading.. Supports the
usual data entry fields (text, numbers, lists, checkboxes etc.), also
unique objects such as picture grids and emoticons. Can fill in forms
online or offline. Completed data can then be sent back via email or by
file. Free evaluation version available.
AssiStat  a Windowsbased package of calculations and analyses useful in educational and psychological research, practice, and in measurement and statistics courses. Designed as a complement to typical statistical packages rather than as a primary analysis tool, it picks up where primary analysis packages usually fall shortin performing secondary analyses like correction of correlations for restriction in range or lessthanperfect reliability, and other specialized analyses and calculations usually not available in standard packages without special programming. Free demo available. StatPac Survey Software  to design andimplement surveys, and to acquire, manage and analyze data from surveys. Supports multiply data types and question formats, multilanguage spellchecking, large files (2,000 variables & 10,000,000 cases, basic statistics (crosstab & banner tables) & graphics, automatic coding of text responses, and data import / export capabilities. Optional Web Survey Module and Advanced Statistics Module (curve fitting, multiple regression, logistic regression, factor, analysis of variance, discriminant function, cluster, and canonical correlation). A demo version is available (limited to 35 cases). NewMDSX  software for Multidimensional Scaling (MDS), a term that refers to a family of models where the structure in a set of data is represented graphically by the relationships between a set of points in a space. MDS can be used on a variety of data, using different models and allowing different assumptions about the level of measurement. This site offers a free month trial of the Windows version; a completely free copy of constituent programs, notes, documentation, test Input& Output in MSDOS; a notforprofit full Windows copy priced at cost; and a site with a range of data, crossreference, & information. GLIMMIX  a powerful approach to segmentation based on latent class models. Analysis of brand choice, purchase frequency and preference data. CORWIN  a program for correspondence analysis, which decomposes relations in a twoway table. ConTEST  a decision support system for assembly of educational and psychological tests from item banks. MUDFOLD (Multiple UniDimensional unFOLDing)  for analyzing proximity data (e.g., attitudes, preferences, or choices) with the Coombsian unfolding model. WINMIRA  Latent Class Analysis (LCA), the Rasch model (RM), and the Mixed Rasch model (MRM) and Hybrid models (HYBRID). TRasch  exact or nonparametric tests for the Rasch model. LPCMWIN  a menudriven program to apply ‘Linear Partial Credit Models’ in item analysis and measurement of change. Kwalitan  for analysis of qualitative data, such as protocols of interviews, articles, and annual reports. 
Excel Spreadsheets and AddIns:
Completely Free... can be freely downloaded and used in their fullyfunctional mode (no strings attached)  Free, but... "demonstration" or "student versions" of commercial packages; can be freely downloaded, but are usually restricted or limited in some way. 
PopTools
 Windows DLL for Excel 97 and 2000 (PC's only). Facilitates analysis
of matrix population models & simulation of stochastic
processes. Adds a new menu item and installs many powerful functions:
matrix decompositions (Cholesky, QR, singular values, LU),
eigenanalysis (eigenvalues and eigenvectors of square matrices) and
formulas for generation of random variables (Normal, binomial, gamma,
exponential, Poisson, logNormal). Also has routines for iterating
spreadsheets to run Monte Carlo simulations, conduct randomisation
tests (including the Mantel test) and calculate bootstrap statistics.
Some facilities for maximumlikelihood parameter estimation, and some
other generally useful functions. Free download from website, which
also has documentation, examples, and related links. RegressIt  An Excel addin for teaching and applied work. Performs multivariate descriptive analysis and ordinary linear regression. . Creates presentationquality charts in native editable Excel format, intelligently formatted tables, high quality scatterplot matrices, parallel time series plots of many variables, summary statistics, and correlation matrices. Easily explore variations on models, apply nonlinear and time transformations to variables, test model assumptions, and generate outofsample forecasts. Includes audit trail and organization features: output stored in separate worksheets, date/time/username worksheet stamps, unique model names in all table and chart titles, and an additional worksheet with sidebyside comparisons of models. SimulAr  Provides a very elegant pointandclick graphical interface that makes it easy to generate random variables (correlated or uncorrelated) from twenty different distributions, run MonteCarlo simulations, and generate extensive tabulations and elegant graphical displays of the results. EZAnalyze
 enhances Excel (Mac and PC) by adding "point and click"
functionality for analyzing data and creating graphs (no formula entry
required). Does all basic "descriptive statistics" (mean, median,
standard deviation, and range), and "disaggregates" data (breaks it
down by categories), with results shown as tables or disaggregation
graphs". Advanced features: correlation; onesample, independent
samples, and paired samples ttests; chi square; and single factor
ANOVA. EZR Stats  supports a variety of analytical techniques, such as: Benford's law, univariate stats, crosstabs, histograms. Also supports databases such as mySQL, SQLite, MSAccess, MSSQL. Simplifies the analysis of large volumes of data, enhances audit planning by better characterizing data, identifies potential audit exceptions and facilitates reporting and analysis. This language is a Computer Assisted Audit Technique (CAAT) in support of COSO, SAS 78, SAS 99 and analysis required by SarbanesOxley. SSCStat  an Excel addin designed to strengthen those areas where the spreadsheet package is already strong, principally in the areas of data management, graphics and descriptive statistics. SSCStat is especially useful for datasets in which there are columns indicating different groups. Menu features within SSCStat can:
22
Distribution Functions  There is one spreadsheet for each
of the following distribution functions: Beta,
Binomial,
ChiSquare,
Discrete
Uniform, Gamma,
Geometric,
Hypergeometric,
Multivariate
Hypergeometric, Laplace,
Logistic,
Multinomial,
Negative
Binomial, Normal,
Bivariate
Normal, Lognormal,
Pareto,
Poisson,
Rectangular,
Snedecor
F, Studentt,
Triangular,
and Weibull.
Each spreadsheet gives a graph of the distribution, along with the
value of various parameters, for whatever shape and scale parameters
you specify. You can also download a ZIP
file containing all 22 spreadsheets. Samplesize calculator for cluster
randomized controlled trials,
which are used when the outcomes are not completely independent of each
other. This independence assumption is violated in cluster randomized
trials because subjects within any one cluster are more likely to
respond in a similar manner. A measure of this similarity is known as
the intracorrelation coefficient (ICC). Because of the lack of
independence, sample sizes have to be increased. This web site contains
two tools to aid the design of cluster trials – a database of ICCs and
a sample size calculator (along with instruction manuals). DAG_Stat  calculates an enormous number of quantities from a 2 by2 table:
MIX (Metaanalysis with Interactive eXplanations)  a statistical addin for Excel 2000 or later (Windows only). Ideal for learning metaanalysis (reproduces the data, calculations, and graphs of virtually all data sets from the most authoritative metaanalysis books, and lets you analyze your own data "by the book"). Handles datasets with dichotomous & continuous outcomes; calculates Risk Diff, RR, OR, Mean Diff, Hedges's g, Cohen's d; performs standard & cumulative metaanalysis with CI ,z & p; fixed and random effects modeling; Cochran's Q with pvalue; Higgins's I2 and H with CI; and publication bias tests: Rank correlation (taub) test with z & p, Egger's and Macaskill's regression tests with CI, and TrimandFill. Generates numerous plots: tandard and cumulative forest, pvalue function, four funnel types, several funnel regression types, exclusion sensitivity, Galbraith, L'Abbe, Baujat, modeling sensitivity, and TrimandFill. OZGRID  contains over 4000 pages (and growing) of information on Excel and VBA for Excel. Many addon's are for sale, but there is also an enormous amount of totally free content: downloads, a free 24/7 question and answer support forum for MS Office, a free Excel monthly newsletter full of detailed tips, tricks, hacks and more for Excel and VBA. Veryhighprecision Statistical Probability Functions  Provides doubleprecision (16 significant figures) mass , density, cumulative, inverse probability distributions, critical values, and confidence bounds for the geometric, negative binomial, binomial, Poisson, hypergeometric, negative hypergeometric, exponential, normal, chisquare, gamma, Student t, Fisher F and beta; noncentral gamma, chisquare, beta, t and F; and the mixed GammaPoisson, BetaBinomial, and BetaNegativebinomial distributions. The routines are programmed in VBA, embedded within an Excel spreadsheet that illustrates the usage of each of them. DE Histograms  an Excel addin that provides comprehensive descriptives stats, histograms, outlier detection, normality testing, and much more. Exact confidence intervals for samples from the Binomial and Poisson distributions  an Excel spreadsheet with several builtin functions for calculating probabilities and confidence intervals. (42k long). BiPlot  by Ilya Lipkovich and Eric P. Smith, of Virginia Tech. A userfriendly addin for Excel to draw a biplot display (a graph of row and column markers from data that forms a twoway table) based on results from principal components analysis, correspondence analysis, canonical discriminant analysis, metric multidimensional scaling, redundancy analysis, canonical correlation analysis or canonical correspondence analysis. Allows for a variety of transformations of the data prior to the singular value decomposition and scaling of the markers following the decomposition. Statistical Process Control (SPC) and Reliability spreadsheets from John Zorich's web site  designed to simplify activities in Production and R&D. Formally validated to be "GMP" and "Part 11" compliant . Free spreadsheets include:
Lifetable  does a full abridged current life table analysis to obtain the life expectancy of a population. Furthermore, one can calculate Potential Gains in Life Expectancy (PGLE) after removing cause k, considering competing causes of death; the (Premature) Years of Potential Life Lost (YPLL), this is the number of person years added to the total number of person years lived in a population if cause of death k would be removed; the Standardized Mortality Ratio (SMR), standardized numbers per 100,000 and the Comparative Mortality Figure (CMF) can also be calculated. From the Downloads section of the QuantitativeSkills web site. Intracorrelation  does intra correlation calculations for dichotomous or binary yes/no type outcome variables according to two different methods proposed for the single cluster one by Fleiss and another one by Bennett et.al. A third spreadsheet concerns a method for two clusters by Donner and Klar. You will have to insert your own data by overwriting the tables in the second (total number of positive responses) and third (total number of negative responses) or fourth column (total number). From the Downloads section of the QuantitativeSkills web site. Weighted Least Squares Linear Fits  an Excel addin from Philip Kromer (Univ. of Texas) 
XLStatistics
 a set of Excel (ver 5+) workbooks for statistical analysis of data.
A stepbystep guide to data analysis with separate workbooks for
handling data with different numbers and types of variables. Contains
most standard analyses, analyses using only summary data, power /
sample size , nonparametrics, curve fitting , nonlinear regression,
analysis for 2x2 tables. XLStatistics is not an Excel addin and all
the working and code is visible. A free version for analysis of 1 and
2variable data is available.
XLMathematics  A set of Excel (Ver 5+) for mathematical computations: graphing , calculus (computing limits, computing and graphing derivatives and/or tangent lines, evaluating integrals using various techniques), Linear algebra (GaussJordan elimination, allowing stepbystep views). Analyseit  includes over 30 parametric & nonparametric statistical functions, including multiple linear regression analysis, ANOVA, & chisquare statistics. A separate specialized package for clinical method evaluation provides NCCLS and IFCC procedures for accuracy & imprecision. Statistical Process Control (SPC) and Reliability spreadsheets from John Zorich's web site  designed to simplify activities in Production and R&D. Formally validated to be "GMP" and "Part 11" compliant . Demo's of spreadsheets include:

Programming Languages and Subroutine Libraries:
Completely Free... can be freely downloaded and used in their fullyfunctional mode (no strings attached)  Free, but... "demonstration" or "student versions" of commercial packages; can be freely downloaded, but are usually restricted or limited in some way. 
MuPAD
 a very powerful and general computerized algebra system, developed
at the University of Paderborn, now distributed by SciFace Software. In
the same category as Mathematica and Maple, it does numerical
calculations, symbolic manipulation (algebra, differentiation &
integration), graphing, and programming. A free "lite" (but still very
powerful) version for PC and Mac can be downloaded. Statistics101  executes programs written in the easytolearn Resampling Stats statistical simulation language. You write a short, simple program in the language, describing the process behind a probability or statistics problem. Statistics101 then executes your Resampling Stats model thousands of times, each time with different random numbers or samples, keeping track of the results. When the program completes, you have your answer. Runs on Windows, Mac, Lunux  any system that supports Java. R  a programming language and environment for statistical computing and graphics. Similar to S or Splus (will run most S code unchanged). Available for Windows, various Unix flavors (including Linux), NextStep and Mac. Provides a wide variety of statistical (linear and nonlinear modelling, classical statistical tests, timeseries analysis, classification, clustering, ...) and graphical techniques, and is highly extensible. Welldesigned publicationquality plots can be produced, including mathematical symbols and formulae where needed. The R environment includes:
ILNumerics  a numerical library for .NET that turns C# into a 1st class mathematical language. It offers both scientists and software developers convenient syntax (similar to Matlab), toolboxes for statistical functions and machine learning, high performance, wide platform support and 2D and 3D visualization features. There's a free "Community" edition and a payfor "Professional" edition. Both have the same features and capabilities; they differ in how you would redistribute them in your own software products. Zelig  an addon for R that can estimate, help interpret, and present the results of a large range of statistical methods. It translates hardtointerpret coefficients into quantities of interest; combines multiply imputed data sets to deal with missing data; automates bootstrapping for all models; uses sophisticated nonparametric matching commands which improve parametric procedures; allows oneline commands to run analyses in all designated strata; automates the creation of replication data files so that you (or anyone else) can replicate the results of your analyses (hence satisfying the replication standard); makes it easy to evaluate counterfactuals; and allows conditional population and superpopulation inferences. It includes many specific methods, based on likelihood, frequentist, Bayesian, robust Bayesian, and nonparametric theories of inference. Zelig comes with detailed, selfcontained documentation that minimizes startup costs for Zelig and R, automates graphics and summaries for all models, and, with only three simple commands required, generally makes the power of R accessible for all users. Zelig also works well for teaching, and is designed so that scholars can use the same program with students that they use for their research. Apophenia  a statistics library for C. It provides functions on the same level as those of the typical stats package (OLS, probit, singular value decomposition, &c.) but doesn't tie the user to an ad hoc language or environment. Octave  a highlevel mathematical programming language, similar to MATLAB, for numerical computations  solving common numerical linear algebra problems, finding the roots of nonlinear equations, integrating ordinary functions, manipulating polynomials, and integrating ordinary differential and differentialalgebraic equations. It is easily extensible and customizable via userdefined functions written in Octave's own language, or using dynamically loaded modules written in C++, C, Fortran, or other languages. Runs under Linux and Windows. J  a modern, highlevel, generalpurpose, highperformance programming language. Runs on Windows, Unix, Mac, and PocketPC handhelds. J runs both as a GUI and in a console (command line). Much like APL, but uses "conventional" symbols, rather than APL's a specialized character set. J is particularly strong in the mathematical, statistical, and logical analysis of arrays of data. J systems have:
Matvec  an object oriented programming language with extensive statistical capabilities. Can handle problems ranging from matrix and vector manipulation to the analysis of linear and generalized linear mixed models. Runs in Linux and Windows environments; has a commandline (nonGUI) user interface, and a strong "Unixlike" flavor. mle  Maximum Likelihood Estimation  a simple programming language for building and estimating parameters of likelihood models. Originally designed for survival models, but the language has evolved into a generalpurpose tool for building and estimating general likelihood models. Available for Windows and Linux; also provides User Manual, Reference Manual, and Quick Reference Card. Ox  an objectoriented matrix programming language with a comprehensive mathematical and statistical function library. Matrices can be used directly in expressions, for example to multiply two matrices, or to invert a matrix. The major features of Ox are its speed, extensive library, and welldesigned syntax, which leads to programs which are easier to maintain. Versions of Ox are available for many platforms. The "Console" version can be freely downloaded for academic and research use; the "Professional" version must be purchased. Mx  a matrix algebra interpreter and numerical optimizer for exploration of matrix algebra. Many builtin fit fuctions for structural equation modeling and other statistical modeling. Has fitting fuctions like those in LISREL, LISCOMP, EQS and CALIS, along with facilities for maximum likelihood estimation of parameters from missing data structures, under normal theory. Users can easily specify complex 'nonstandard' models, define their own fit functions, and perform optimization subject to linear and nonlinear equality or boundary constraints. JDB  Relational Database and Elementary Statistics for a Unix environment. Useful for manipulating experimental data (joining files, cleaning data, reformatting for input into other programs). Computes basic statistics (mean, std. dev., confidence intervals, quartiles, ntiles, percentiles, histograms, correlations, zscores, tscores. B/D  an interactive programming language for a priori and diagnostic analyses of Bayes linear statistical problems (subjective statistical analyses based on expectation and covariance structures, rather than on distributional assumptions). Quickly and easily specify beliefs about quantities of interest, attach data to some or all of those quantities, and carry out the general process of Bayes linear adjustment. Produces interactive Bayes linear influence diagrams for the adjustments, providing simple graphical summaries of the adjustments and accompanying diagnostics. MacANOVA  comprehensive statistical package for the Mac and PC/Windows. MacAnova has macros which are used just like functions. Several macros are built in, and three files of additional macros (general, time series, design of experiments) are distributed with MacAnova. Like S, MacAnova is a programming language with for and while loops, if, else, elseif, break, and a full range of operations including bit manipulation. LispStat  an extensible statistical computing environment for data analysis, statistical instruction and research, and for exploring the use of dynamic graphical methods. Based on an extended subset of Common Lisp, performs elementwise operations on lists and vectors, and adds a variety of basic statistical and linear algebra functions. Graphics system is objectoriented, and can be customized and adapted. Supports linear and nonlinear regression models and generalized linear models. Runs on Mac, Xwindow (UNIX), and MS Windows. 
Resampling
Stats  a different approach to learning statistics and
performing statistical analyses, using simulation with random numbers
instead of complex mathematics. 30day trial version available for Win
95/NT.
OMatrix  an extensive matrix manipulation system (for Windows) with lots of statistical capability. The "Light" version can be freely downloaded. Some capabilities include:
Also provides extensive plotting capabilities, with multiple windows, axis scaling & labeling, titling, freeform text, selectable fonts. Plots exportable to word processors, spreadsheets, etc. Plot Types: line, contour, surface, mesh, bar, stair, polar, vector, error bar, smith charts, and histogram; line plots can contain unlimited points per curve and hundreds of curves per plot; two and threedimensional plotting is supported which provides additional flexibility with contours and surface plots; multiple colors, markers, and line types.

Completely Free... can be freely downloaded and used in their fullyfunctional mode (no strings attached)  Free, but... "demonstration" or "student versions" of commercial packages; can be freely downloaded, but are usually restricted or limited in some way. 
SPSS
Syntax Files  a large collection of SPSS routines for
randomized study design , sampling strategies, metaanalysis, sanple
size for confidence intervals, correlation tests, psychometry and other
areas. The documentation is in Portuguese, but the scripts are usable
asis. You can have AltaVista automatically translate the page into
English by going here,
but do not use the "translated" scripts! The author
has recently added two additional sections (in English)  one for Dyadic Data
Analysis, and one for Simple
and Complex Random Assignment for Experimental Designs
LinkKing  a SAS program to detect duplicate entries in a file, or to link matching records in two files, based on criteria like names (first, middle, last, maiden, nickname), date of birth, gender, and social security number. A graphical interface, a “Link King for Knaves” feature, and a powerful interface for manually reviewing uncertain matches make it easy to use. It features both probabilistic and deterministic record linkage algorithms, phonetic name matching (NYSIIS and Soundex), and many other features for dealing with "mushy matches". 
Completely Free... can be freely downloaded and used in their fullyfunctional mode (no strings attached)  Free, but... "demonstration" or "student versions" of commercial packages; can be freely downloaded, but are usually restricted or limited in some way. 
TextStat
 Free Windows program that analyzes ASCI/ANSI texts and HTML files
(directly from the internet) and produces word frequency lists and
"concordances" (sorted keywordincontext listings). Can traverse an
entire web site, acquiring pages for analysis.
DeltaStat  performs statistical calculations on data from 2D gel experiments quantified in Delta2D. Makes use of R and MySQL to perform much faster than the functions provided in Delta2D. Currently provides two sample ttest, a highly configurable database query, multiple analyses per query to analyze proteins that have both higher and lower expression in control versus experimental groups, and support for experiments with variable numbers of control and experimental replicates. Sampling SIM: Downloadable program (for Mac or Windows) to explore sampling distributions of sample means and proportions. It provides separate windows for building population distributions, drawing and viewing random samples from the population, exploring the behavior of sampling distributions of sample means, and exploring the behavior of confidence intervals. First Bayes  a free, easytouse Windows application for elementary Bayesian Statistics. Performs most standard, elementary Bayesian analyses, including: plotting and summarizing distributions, defining and examining arbitrary mixtures of distributions, analysis of two kinds of linear model (one or more normal samples with common but unknown variance, and simple linear regression), examination of marginal distributions for arbitrary linear combinations of the location parameters, and the generation of predictive distributions. IND  Creation and manipulation of decision trees from data. For supervised classification and prediction in artificial intelligence and statistical pattern recognition. A tree is "grown" from data using a recursive partitioning algorithm to create a tree which (hopefully) has good prediction of classes on new data. IND improves on standard algorithms and introduces Bayesian and MML methods, producing more accurate class probability estimates that are important in applications like diagnosis. For UNIX systems. Currently available only in betatest mode, and only to US citizens. MANET  ("Missings Are Now Equally Treated") Macintosh software for interactive graphics tools for data sets with missing values. Generates missing values chart, histograms & barcharts, boxplots & dotplots, scatterplots, mosaic plots, polygon plots, highlighted boxplots, interactive trellis displays, traces, contextsensitive interrogation, cues, redframing, selection sequences. GrafProg  a Windows graphing program design, copy and save graphs generated by functions or by spreadsheet; also includes some statistical graphing processes. StudioLine Photo Basic  Photo editing software from H&M Software. Add descriptions to images, resize photos for efficient email transmission, print highquality copies, display slideshows, publish webgalleries, safekeep images on CD or DVD. Version 2.2 has a new user interface, dualmonitor support, increased speed and other technical improvements. SmartUpdate feature checks for new versions. Has a webboard for usertouser help. WAFO  Wave Analysis for Fatigue and Oceanography. A toolbox of Matlab (ver. 5.x / 6.x, for Windows & Unix) routines for statistical analysis and simulation of random waves and random loads. Tools are provided for analysis of measured data with routines for estimation of parameters in statistical distributions, estimation of spectra, plotting in probability papers, etc. Has routines for theoretical distributions of characteristic wave parameters from observed or theoretical power spectra of the sea. Another part is related to statistical analysis of fatigue. The theoretical density of rainflow cycles can be computed from parameters of random loads. Has routines is included for modelling of switching loads (hidden Markov models). Also contains general statistical tools. 
Advanced
Grapher (formerly called Serpik Graph)  a very
sophisticated function graphing program  can also plot tables and
perform regression. A 30day fullfunctioned trial version can be
downloaded.
CoPlot 6.2  for publicationquality 2D and 3D scientific graphs (from data and equations), maps, and technical drawings. From CoHort Software. Creates precise technical drawings using drawing objects, genetic maps, field maps, flow charts, apparatus diagrams, circuit diagrams, chemical structures, etc. Text in drawing objects and graphs can include HTMLlike text formatting tags and over 1000 special characters. Supports animated graphs. Exports graphs to .eps, .gif, .jpg, .pdf, .png, .svg, .wmf, and others. Has an autorecorder and macro programming language. Invoke CoPlot from the command line, batch files, shell scripts, pipes, and other programs. Can be used as a graphics server program on a web site. Free timelimited demo version available. Numerous statistical packages from companies acquired by SPSS Corp. Most of these demonstration versions expire after 30 days, and some have other limitations. Available products include:
A large number of software demos are available for downloading from the website of SciencePlus, a distributor of scientific and related software (both full commercial packages and specialist academic tools). The list includes: ACTIV STATS, AGREE, AMOS, AQUAD, BIOFEEDBACK, BOJA, CADEMO, CART, CONTEST, CORWIN, DATADESK, DATA ENGINE, DBMS/Copy, EASYPLOT, EDWIN, ELI, E_PRIME, EQS, EQUITY, EQUIVTEST, ERTS, ERTSLAB, EXAMINER, EXPERT CHOICE, FASTTEST, GBSTAT, GETAREF, GLIMMIX, GOMAP, HIVIEW, HLM, ITEMAN, KWALITAN, LISREL, LPCM, MAPLE V, MELLAB, MEL 2, MICROCAT, MINITAB, MUDFOLD, NQUERY ADV., NSDSTAT+, OBSEVER, PARELLA, PEAKFIT, PLCA, POLYANALYST, RASCAL, REHACOM, SCRUTINY, SIGMA PLOT, SIGMA SCAN PRO, SIGMA STAT, SOLAS, STATISTICA, STRAD, STREAMS, SUPERLAB PRO, SUPERLAB LT, SYSTAT, TABLECURVE 2D/3D, TEXTANALYST, TRASCH, TRIQ, UNISTAT, Vienna Test System, WINMIRA, WINROSA, XCALIBRE 
Other Links to Collections of Free Software: