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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.
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 →Is the chi-square test one-tailed or two-tailed?
Why a chi-square test reads only the right end of its curve yet detects differences in any direction, and why its p value is never halved.
Read the answer →t test vs ANOVA with two groups: are the assumptions really different?
Why a pooled t test and a one-way ANOVA on two groups give the same p value, and why their normality assumptions are the same thing stated two ways.
Read the answer →Need more than an answer?
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