Specifications

Contents:

• Core Features
• Data Import and Export
• Help and References
• Data Preparation
• Descriptive Statistics
• Confidence Intervals
• Graphics/Charts/Plots
• Parametric Methods
• Nonparametric Methods
• Regression and Correlation
• Analysis of Variance
• Agreement Analysis

• Meta-analysis
• Survival Analysis
• Distribution Functions
• Chi-square Contingency Tables
• Exact Tests on Counts
• Proportions
• Rates
• Sample Size Estimation
• Randomization
• Clinical Epidemiology
• System Requirements
• Availability

Core Features

• Exceptionally easy to use
• Statistics guide built into the software
• Includes all common statistical methods
• State-of-the-art computational methods for fast and reliable results (e.g. bootstrap around 100 times faster than R)
• Can link easily with Microsoft Excel
• Delivered and supported directly via the web
• Designed for both front line research and education
• Built upon twenty years of research and development

[top]

Data Import and Export

• Workbooks (similar to Excel spreadsheet)
• Maximum worksheet capacity is 64K columns by 1M rows
• Read and write Microsoft Excel files (2013/2010/2007 or 97-2003)
• Import any common spreadsheet data
• Import text based data (formatted or plain)
• Read/write reports in portable rich text format (RTF) or HTML
• Windows metafile scaleable graphics (can edit components in Word)

[top]

Help

• Statistics guide/text on-line
• Comprehensive scientific references for methods
• Context-sensitive help with results/reports
• Powerful educational tool
• Global academic user base

[top]

Data Preparation

• On-line algebraic calculator
• Apply user-defined functions/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
• Anthropometric standardization (child growth charts)
• All pairwise differences, means and slopes
• Dummy/design/indicator variable generation
• Convert text to numbers
• Generate random numbers (uniform, normal, chi-square, F, t, binomial, Poisson, gamma, exponential)
• Categorise a continuous variable
• Extract a subset of data by search rules
• Tabulate and detabulate row/column classified data

[top]

Descriptive Statistics

• Univariate descriptive statistics (count, mean, standard deviation, standard error, confidence interval, skewness, kurtosis, median, quartiles, range and a user defined quantile)
• Frequencies
• Tabulations and crosstabs
• Time series summary with area under time-concetration curve for pharmacokinetics

[top]

Confidence Intervals

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

[top]

Graphics/Charts/Plots

• Bar/column charts
• Frequency distribution histograms
• Spread plots, dotplots
• Box & whisker plots
• Normal plots, nomal scores
• Forest (Cochrane, 'blobogram') plots
• Scatter plots, line charts and error bar plots
• Ladder, pairwise change plots
• Agreement plots
• Survival curves
• Residual and diagnostic plots with regressions
• Area under ROC curves
• Population pyramids
• Control (statistical process) charts

[top]

Parametric Methods

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

[top]

 Non-parametric Methods

• Exact P values and confidence intervals
• Mann-Whitney (Wilcoxon rank sum)
• Wilcoxon signed ranks
• Spearman and Kendall rank correlations
• Cuzick's test for trend
• Two sample Smirnov
• Exact confidence intervals for median and other centiles
• 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
• LOESS curve fitting
• Nonparametric linear regression

[top]

Regression and Correlation

• Simple linear regression and Pearson's correlation
• Multiple/general linear with best subset selection
• Principal components analysis (PCA) with Cronbach's alpha
• Influential data identification, residual diagnostics and plots
• Grouped linear regression with analysis of covariance
• Various linearized estimates
• Probit analysis (probit or logit), dose response, ED50, LD50
• Polynomial regression with area under curve and back interpolation
• Logistic regression with confidence intervals for cross classification and odds ratios, and bootstrap
• Conditional logistic regression for matched case-control studies
• Poisson regression, relative risk, incidence rate ratio
• Curve fitting
• Cox regression, proportional hazards, hazard ratio
• Kendall and Spearman rank correlations with confidence intervals

[top]

Analysis of Variance

• Randomized Block: one way, two way, two way with repeats
• Multiple comparisons: 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

[top]

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.)
• Berry-Mielke Universal R

Meta-analysis

• Exact pooled estimates given wherever practical
• Odds ratio
• Peto odds ratios
• Relative risk
• Risk difference
• Effect size (d, g)
• Incidence rate difference and ratio
• Proportion
• Correlation
• Summary data meta-analysis
• Forest plots and exact confidence intervals
• L'Abbé plots
• Funnel plots
• Egger et al. and Begg & Mazumdar bias tests
• I-square confidence intervals and heterogeneity summary

[top]

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
• Logrank test with trend, exact hazard ratios, stratified
• Generalized Wilcoxon tests (Peto-Prentice, Gehan-Breslow or Tarone-Ware weights)
• Wei-Lachin multivariate comparison of two groups
• Cox regression, proportional hazards, multivariate hazard ratio

[top]

Distribution Functions

• Normal, Gaussian
• Student t
• F
• Chi-square
• Studentized range Q
• Binomial
• Poisson
• Spearman rho
• Kendall tau
• Non-central t
• Gamma
• Many other distribution functions behind other methods: hypergeometric, Kolmogorov-Smirnov, Mann-Whitney U etc.

[top]

Chi-square Contingency Tables

• 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 matched pairs (and k by k extension)
• Maxwell (agreement, equivalence)
• Mantel-Haenszel and Woolf with plots
• Generalised Cohrane-Mantel-Haenszel for R by C by K tables
• Goodness of fit

[top]

Exact Tests on Counts

• Fisher exact (2 by 2 tables)
• Fisher-Irwin (R by C tables)
• Gart confidence intervals for odds ratios
• Liddell exact alternative to McNemar for matched pairs
• Sign test, binomial test
• Poisson rate or count confidence interval

[top]

Proportions

• Single
• Paired
• Two independent
• Exact confidence intervals

[top]

Rates

• Exact Poisson confidence intervals for rates or counts
• Exact analysis of rate ratios
• Direct standardization
• Indirect standardization and standardized mortality ratio (SMR)
• Standardize and compare two rates
• Incidence rate meta-analysis

[top]

Sample Size Estimation

• For comparison of means (paired, unpaired)
• For comparison of proportions
  • Independent case-control
  • Independent cohort
  • Matched case-control
  • Paired cohort
• For population surveys
• For survival analysis
• For correlation

[top]

Randomization

• Uses robust random number generator (Mersenne-Twister)
• Intervention-control pairs (with balanced allocation)
• Allocation to independent intervention and control groups
• Block randomization
• Preference group allocation
• Random series of integers from X to Y
• Generate random numbers from distributions (uniform, normal, binomial, Poisson, beta, F, t, chi-square, gamma, lognormal, Cauchy, Weibull, exponential, logistic, negative binomial) for simulation

[top]

Clinical Epidemiology

• Prospective risk: relative risk, risk reduction and population attributable risk
• Retrospective risk: odds ratio, population attributable risk
• Diagnostic test analysis
• Likelihood ratios in diagnostic test series
• Number needed to treat (NNT) with exact confidence intervals
• Screening test error probabilities (Bayes)
• Kappa (optional user defined weights) and Scott's pi agreement
• Incidence rate analysis
• Growth charts (anthropometric z-scores)

[top]

System Requirements

• Any version of Microsoft Windows that is supported by Microsoft running .Net Framework version 6.1 or later
• At least 1GB memory free
• Some users run StatsDirect on a Mac with Microsoft Windows installed using virtualisation (e.g. via Vmware Fusion or Parallels)
• Previous StatsDirect version 2 is available for old Windows NT, 2000, XP, Vista, or 7 without Service Pack 1, including 32-bit versions

[top]

Technical history

• Revisions / version history
• Technology history

[top]