Practical, no-jargon guides to help you choose the right test, check assumptions, and report results correctly. Free and useful whether or not you use GraphHelix.
An interactive decision flowchart that walks you through your research design — number of groups, variable types, and assumptions — to recommend the right test.
Shapiro-Wilk tests, Q-Q plots, and what to do when your data isn't normally distributed. A practical guide to assumption checking before parametric tests.
The parametric vs. non-parametric decision explained with examples. When assumptions matter, when they don't, and how to report both correctly.
Concrete examples of APA 7th edition ANOVA reporting: F-statistics, degrees of freedom, p-values, effect sizes, and post-hoc comparisons — ready to paste into your manuscript.
What effect sizes mean, when journals require them, and how to interpret Cohen's d, eta-squared, partial eta-squared, and R-squared with practical benchmarks.
Free toolCalculate the number of participants your study needs. Supports t-tests, ANOVA, chi-square, correlation, regression, two proportions, and animal studies. No install, no account required.
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