Statistics in Psychology
Practical guides on effect sizes, reliability, study design, and more — written for psychology students and researchers.
All Articles
T-Test: Complete Guide to Calculation and APA 7
Learn how to choose, calculate, interpret, and report t-tests in APA 7, with formulas, worked examples, assumptions, effect sizes, and practical guidance.
Hedges' g vs Cohen's d: When, Why, and How to Choose (With Formulas)
Compare Hedges' g and Cohen's d effect sizes: understand small-sample bias, calculation formulas, correction factor J, and APA 7th edition reporting recommendations.
What Is Cohen's d? Formula, Interpretation, and APA Reporting Guide
Master Cohen's d effect size: learn the exact formula, pooled standard deviation calculations, benchmark interpretations (0.2, 0.5, 0.8), and APA 7th edition reporting templates with worked examples.
Why P-Values Aren't Enough: The Case for Effect Sizes in Psychology
Discover why p-values alone are insufficient in psychology research. Learn the difference between statistical and practical significance, sample size sensitivity, and APA 7th edition effect size guidelines.