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Precision and sample size

Before you conduct your experiment, determine the sample size needed to achieve the desired precision of a confidence interval. Do you plan to use CIs for means or variances, one sample or two samples, independent data or paired data? Do you want to use your own CI method? Use Stata's ciwidth commands or interactive Control Panel to compute CI precision and sample size, create customized tables, and automatically graph the relationships between sample size, CI width, and probability of CI width for your planned study. And much more.

Overview of precision and sample-size analysis.
Watch Precision and sample-size analysis.


  • Means
  • Variances
  • One sample
  • Two samples
  • Independent data
  • Paired data
  • Your own method

Solve for

  • Sample size
  • CI width
  • Probability of CI width

Specify lists of

  • Sample sizes
  • CI widths
  • Probabilities of CI width
  • Ratios of sample sizes
  • And more

Multiple scenarios using

  • All combinations of values
  • Parallel lists of values


  • Automated
  • Customized


  • Automated
  • Customized
  • Simple or comparative

Control panel interface

  • Select analysis type from descriptive summaries
  • Specify analysis interactively
  • Automated tables and graphs
  • Customize tables and graphs
  • Command interface too (of course)

Save results to dataset

Additional resources

Also see power and sample-size analysis for hypothesis tests.