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Basic statistics

Summaries

  • Arithmetic, geometric, and harmonic means, and corresponding confidence intervals
  • Medians and percentiles
  • Measurement of central tendency
  • Skewness and kurtosis
  • Confidence intervals
    • Means
      • Normal
      • Exact Poisson
    • Proportions
      • Exact binomial (Clopper–Pearson)
      • Wald
      • Wilson
      • Jeffreys
      • Agresti
    • Variance
      • Normal
      • Bonett
  • Ratios, proportions, and totals
    • Confidence intervals
    • Standard errors
    • Over groups
    • Robust and cluster–robust SEs
    • Intragroup tests

Tables and tabulations

  • 1- , 2- , n-way
  • Pearson's chi-squared
  • Likelihood-ratio chi-squared
  • Cramér's V
  • Fisher's exact (2 x 2 and r x c)
  • Goodman and Kruskal's gamma
  • Kendall's tau
  • Cell statistics
    • Expected count
    • Contribution to Pearson chi-squared
    • Contribution to likelihood-ratio chi-squared

Tables of summary statistics

  • Over groups and/or variables
  • Statistics may include mean, count, sum, min, max, range, standard deviation, variance, variation coefficient, standard error of mean, skewness, kurtosis, median, percentiles, and interquartile range
  • Results from any summary-statistics command

Creation of datasets of summary statistics

  • Statistics by group or subgroup of observations
  • Statistics: mean, standard deviation, count, min, max, median, percentiles, and interquartile range

Pairwise comparisons of means

  • Pairwise differences in means with tests and confidence intervals
  • Multiple-comparison adjustments: Bonferroni, Šidák, Scheffé, Tukey HSD, Duncan, and Student–Newman–Keuls adjustments
  • Group comparisons that are significant
  • Balanced and unbalanced data

t tests

  • One sample
  • Two independent samples
  • Two paired samples
  • Based on summary data (ttesti)

z tests

  • One sample
  • Two independent samples
  • Two paired samples
  • Support for clustered data
  • Based on summary data (ztesti)

Tests of proportions

  • One sample
  • Two sample
  • Support for clustered data
  • Based on summary data (prtesti)

Effect sizes

  • Comparison of means
    • Cohen's d
    • Hedge's g
    • Glass's Δ
    • Point/biserial correlation
    • Confidence intervals
  • Variance explained by regression and ANOVA
    • Eta-squared—η2
    • Omega-squared—ω2
    • Confidence intervals

Other common tests

  • Binomial (one-sample) test
  • Bartlett's test
  • Chi-squared (one-sample) variance test
  • Variance ratio (two-sample) F test

Correlations

  • Pearson simple and partial
  • Semipartial
  • Spearman's rank correlation Updated
  • Kendall's rank correlation
  • Intracluster
  • Cronbach's alpha
  • Tetrachoric
  • Canonical (multivariate) correlations
  • Intraclass

Factor variables

  • Automatically create indicators based on categorical variables
  • Form interactions among discrete and continuous variables
  • Include polynomial terms
  • Perform contrasts of categories/levels
Watch Introduction to Factor Variables in Stata tutorials

Additional resources

See New in Stata 18 to learn about what was added in Stata 18.