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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.
Does k-means make assumptions? Its drawbacks explained
Why k-means, though 'just an optimization', behaves as if clusters were round, equally spread and equally sized, and what happens when they are not.
Read the answer →Where should histogram bin edges go when your data are rounded?
When values are recorded to a fixed unit, put histogram bin edges halfway between the possible values. Here is why, and how counts differ.
Read the answer →Skewed data with zeros: is log(x + 1) OK, and what else works?
Why log(x + c) gives results that hinge on an arbitrary constant, and better options for skewed data with zeros: log-link GLMs, two-part models and asinh.
Read the answer →Need more than an answer?
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