Sample Size Calculator
Prior to designing a trial, authors must determine how many subjects should be included in a trial in order to have adequate statistical power. There are a variety of different equations depending on the trial design and the type of outcome being measured. Check out the ClinCalc Sample Size Calculator.
Post-hoc Power Calculator
Following the completion of a trial, authors (or reviewers) may want to calculate the statistical power of a trial. Although there are pitfalls in using post-hoc power analysis, which are described in the article, post-hoc power is commonly used in medical literature. Check out the ClinCalc Post-hoc Power Calculator.