Core Features

• Exceptionally easy to use
• Statistics guide built into the software
• Includes all common statistical methods
• State-of-the-art computational methods for reliable results
• Can link easily with Microsoft Excel
• Delivered and supported directly via the web
• Designed for both front line research and education
• Built upon fifteen years of research and development

Data in/out

• Workbooks (similar to Excel spreadsheet)
• Worksheet capacity is 256 columns by 65,000 rows
• Excel link (data link to put StatsDirect into Excel)
• Import any common spreadsheet data
• Import text based data (formatted or plain)
• Read/write reports in portable rich text format (RTF)
• Windows metafile scaleable graphics (can edit components in Word)

Help

• Statistics guide/text on-line
• Full academic references and validation of functions
• Full context-sensitive integration of help
• Powerful educational tool
• Strong academic user base
• Support via the web

Data Manipulation

• On-line algebraic calculator
• Apply formulae to data in worksheet
• Many arithmetic, trigonometric, algebraic and logical functions
• Sort in worksheet (like Excel) or as separate function
• Rotate/transpose blocks of data in worksheet
• Ranks and normal scores (van der Waerden, Blom and expected normal order)
• Combine or split data by group identifier or separate columns
• Transformations (many, including ladder of powers)
• Standardization
• All pairwise differences, means and slopes
• Dummy/design variable generation
• Interpret text and dates as numbers
• Generate random numbers (uniform, normal, chi-square, F, t, binomial, Poisson, gamma, exponential)
• Categorisation of continuous data
• Extraction of data subsets by search rules
• Tabulation and detabulation

Descriptive Statistics

• Counts, capture, mean (& conf. interval), standard deviation, standard error, skewness, kurtosis, median, quartiles, range and a user defined quantile
• Frequencies
• Crosstabs

Confidence Intervals

• Strong emphasis on confidence interval inference
• Exact methods used wherever practical
• Additional mid-P coverage given with many intervals
• Help on interpretation

Pictorial Statistics

• Business charting tool
• Frequency distribution histograms
• Box & whisker and spread plots
• Normal plots
• Forest (Cochrane, 'blobogram') plots
• Scattergrams and error bar plots
• Ladder, agreement and survival plots
• Residual, ROC and diagnostic plots
• Population pyramids
• Lorenz plots
• Control charts
• Plot mathematical functions

Parametric Methods

• Student's t tests for single, paired (including agreement stats) and unpaired samples
• Normal distribution (Z) tests
• Reference ranges (normal, log-normal and percentile-based)
• F (variance ratio test)
• Shapiro-Wilk test for non-normality

 Non-parametric Methods

• Mann-Whitney
• Wilcoxon signed ranks
• Spearman's & Kendall's rank correlations with confidence intervals
• Cuzick's test for trend
• Two sample Smirnov
• Quantile confidence intervals (exact)
• Homogeneity of variance, including Breslow-Day test
• Friedman, Cochrane Q, Kruskal Wallis with multiple contrasts
• Chi-square goodness of fit
• Gini coefficient of inequality with bootstrap confidence intervals
• Simpson and Shannon diversity indices with bootstrap confidence intervals

Regression & Correlation

• Simple linear & Pearson's correlation
• Multiple/general linear
• Best subset selection
• Principal components analysis with Cronbach's alpha for deletions
• Influential data identification
• Grouped linear regression with analysis of covariance
• Various linearized estimates
• Probit analysis (probit or logit)
• Polynomial regression with area under the curve and back interpolation
• Binary logistic regression with confidence intervals for cross classification and odds ratios
• Bootstrapping of binary logistic regression
• Conditional logistic regression for case-control studies
• Poisson regression
• Residual plots and analysis
• Curve/line plotting
• Cox regression
• Kendall's and Spearman's rank correlations with confidence intervals

Analysis of Variance

• Randomized Block: one way, two way, two way with repeats.
• Multiple contrasts: Tukey(-Kramer), Dunnett, Neuman-Keuls, Scheffé and Bonferroni
• Nonparametric: Kruskal-Wallis and Friedman with multiple contrasts
• Crossover
• Latin squares
• Nested/Hierarchical two way
• Homogeneity of variance
• Analysis of agreement

Agreement Analysis

• Agreement of continuous data (intra-class correlation etc.)
• Agreement of categorical data (kappa or two or more raters and two or more categories etc.)
• Reliability and reducibility (Cronbach's alpha for scale reliability etc.)

Meta-analysis

• Exact pooled estimates given wherever practical
• Odds ratios
• Peto odds ratios
• Relative risk
• Risk difference
• Effect size (d, g)
• Incidence rate difference and ratio
• Proportions
• Forest (Cochrane) plots and exact confidence intervals
• L'Abbé plots
• Bias assessment plots
• Egger et al. and Begg & Mazumdar bias tests

Survival Analysis

• Kaplan-Meier estimates with survival plots
• Confidence intervals for mean and median survival times
• Follow-up (Berkson-Gage) life tables
• Abridged current life tables
• Peto's Logrank with trend test and exact hazard ratios - can be stratified
• Generalized Wilcoxon test (Peto-Prentice, Gehan-Breslow or Tarone-Ware weights)
• Wei-Lachin multivariate comparison of two groups
• Cox regression

Distribution Functions

• Normal
• Student's t
• F
• Chi-square
• Studentized range Q
• Binomial
• Poisson
• Spearman's rho
• Kendall's tau
• Non-central t
• Many reliable algorithms integral to other functions e.g. hypergeometric, Kolmogorov-Smirnov, Mann-Whitney U etc..

Chi-square

• 2 by 2 with confidence interval for odds ratio or relative risk
• 2 by k with trend
• r by c with trend and G square
• McNemar's (extended to k by k matched pairs)
• Maxwell's
• Mantel Haenszel and Woolf with plots
• Cohrane-Mantel-Haenszel generalized tests for r by c by k tables
• Goodness of fit

Sign & Exact Contingency

• Fisher's exact (up to r by c tables)
• Gart confidence intervals
• Liddell's exact alternative to McNemar's
• Sign test with confidence intervals

Proportions

• Methods for single, paired and unpaired
• Robust ("exact") confidence intervals

Rates

• Exact confidence intervals for Poisson rates
• Exact analysis of rate ratios
• Direct standardization
• Indirect standardization and standardized mortality ratios (SMRs)
• Comparison of directly standardized rates

Sample Sizes

• For comparison of means
• For comparison of proportions (including case-control and 1:m matching)
• For population surveys
• For survival analysis
• For correlation

Randomization

• Based on reliable pseudo-random number generators
• Intervention-Control allocation (including balanced groups)
• Balanced allocation to intervention and control groups
• Fixed and random block randomization
• Uses random number generator (Mersenne-Twister) robust for Monte Carlo simulation and bootstrapping
• Random deviates (uniform, normal, binomial, Poisson, beta, F, t, chi-square, gamma, lognormal, Cauchy, Weibull, exponential, logistic, negative binomial) for simulation

Miscellaneous

• Relative risk, risk reduction and population attributable risk with confidence intervals
• Diagnostic test analysis
• Likelihood ratios with exact confidence intervals
• Risk reductions and number needed to treat with exact confidence intervals
• False result probabilities
• Kappa (optional user defined weights) and Scott's pi agreement statistics
• Incidence rate analysis

System Requirements

• Microsoft Windows Vista/XP/NT/2000/ME/98
• At least 256MB of RAM, 1GB recommended

Availability

Available for purchase via the web.
Official orders taken from academia, public sector and corporations.
Special pricing for individuals, students and developing world.
See learning with StatsDirect for low cost learning arrangements.

Independent Reviews

Lipp A. The Journal of Public Health Medicine; 24(3): 242, September 2002

Freemantle N. British Medical Journal; 321:1536, December 2000

Fitzpatrick V. Biomednet:HMS Beagle; 81, July 2000

Mitchell M. JAMA; 284(15), October 2000

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