Description: Use these for studies examining means or proportions, studies with clustered data, survival analysis, and more.
Link: Statistical calculators
Who is this resource for: Clinical investigators
Who created this resource: This site is run by the University of California San Francisco Clinical and Translational Science Institute.
What does this resource offer: This site includes calculators for the necessary sample size to detect a user-defined effect size or the minimum detectable effect size for a user-defined sample size. The types of studies and analyses accommodated by these calculators are broad and include:
- One group, two independent groups, and paired group designs
- Tests for means, proportions, and correlation
- Clustered data
- Confidence intervals
- Survival analysis
- Likelihood ratio (diagnostic test accuracy)
- Posterior probability of disease
- Pediatric growth
Each calculator includes helpful descriptions of the required inputs. They also include descriptions of the method used for sample size/effect size calculations along with relevant formulas and references. This website also has two tabs at the top: “About Calculating Sample Size” and “Glossary of Terms” which offer explanations of sample size vocabulary as well as study design considerations.
Helpful hints: Don’t miss the “About Calculating Sample Size” and “Glossary of Terms” tabs for more information about sample size calculations.