Plan My Analysis
A few plain-English questions about your study, and out comes a complete, printable analysis plan: the recommended test and why, the assumptions to check, the sample size you'll need (from the same exact power math as the calculator), and a ready-to-fill APA write-up skeleton. Hand it to your supervisor.
A plan, not a promise. This wizard picks a sensible default analysis and a sample size for the effect you specify, but real studies have wrinkles no flowchart sees. Confirm the assumptions, and decide your analysis before you collect data, ideally by preregistering it, so you can't switch tests until something turns up p < .05.
Sample sizes assume 80% power at α = .05 (the field's convention), and are computed with the exact noncentral t, F and χ² distributions, the same engine as the power calculator, where you can vary the power, α and tails.
How to use your plan
- Work through the questions until you reach a recommended test.
- Set the effect size you expect. Pick a benchmark, borrow one from prior literature, or read the "no idea?" note. The sample size updates live.
- Print it with the button on the plan. Only the plan card prints, with a header and this page's URL, so it's a tidy one-pager for a supervisor or ethics application.
- Follow the links to the interactive lesson, the SPSS/JASP walkthrough, the APA formatter (pre-set to your test), and the power curve.
Prefer the quick version?
If you just want the test name, the Which Test Should I Use? chooser is the express lane. This page is its grown-up sibling — it keeps going, all the way to a sample size and a write-up. For the picture side of a thesis, see Which Chart Should I Use?