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- Rather work it out yourself? Try the test chooser below.
Interactive guide
Which statistical test should I use?
Answer a few plain-language questions. You'll get a suggested test, what to check before you trust it, and links to free tools.
A starting point, not a substitute for looking at your data. Design details such as clustering, missing data, and multiple comparisons can change the right answer.
Free resources
Free tools and guides
These live on the DASS site and are free to use.
Tools
Power analysis calculators
Plan sample size for t-tests, ANOVA, correlations, chi-square, and multilevel designs.
Open calculators →APA 7 results formatters
Turn statistical output into clean, copy-ready APA sentences. Runs in your browser.
Open formatters →Check a reported p-value
Recompute the exact p from a t, F, chi-square, or correlation statistic and compare it to what was reported.
Check a p-value →Guides
Answers
Recent questions, answered
Plain-language answers to statistics questions people are asking.
How are alpha and beta (Type I and Type II error rates) related?
Why lowering alpha raises beta, why the trade-off is not linear or a fixed ratio, and what a Bonferroni correction does to power.
Read the answer →How do you compare a short ordinal rating scale between two groups?
t test, Mann-Whitney or chi-square for a 1-4 rating item: what each one tests, how they compare in a simulation, and how to report the result.
Read the answer →Standard error vs standard deviation: what is the difference?
The SD describes how individual values vary; the standard error describes how a sample mean varies. How to tell which one you need, totals included.
Read the answer →Need more than an answer?
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