Guides

The decisions behind
the number.

A calculator gives you a sample size. These guides help you choose the inputs and defend them to a committee, a reviewer, or a funder. Every worked example is checked in R.

Planning inputs

Choosing an effect size you can defend

Three defensible ways to pick the effect size, the mistakes reviewers catch, and a sentence to adapt for your proposal.

Reference

Methodology

The formulas, assumptions, and validation against R behind every design in the calculator.

Step by step

How to do a power analysis for your study

Six decisions from research question to sample size, with the adjustments most plans forget: attrition, covariates, clustering and multiple outcomes.

Coming next