Statistical Concepts

Plain-language tutorials covering everything from effect size to regression. Each guide includes formulas, worked examples, and APA reporting templates.

Descriptive Statistics

Master descriptive statistics: learn about mean, median, mode, standard deviation, variance, and range. Know when to use each measure for your research data.

beginner

Inferential Statistics

Chi-Square Test of Independence

Learn how to perform a chi-square test of independence to analyze associations between categorical variables, with formulas, examples, and Cramer's V.

beginner

Independent Samples t-Test

Learn how to conduct and interpret an independent samples t-test, including assumptions, formulas, worked examples, and APA reporting guidelines.

beginner

One-Way ANOVA

Learn how to conduct a one-way ANOVA to compare three or more group means, including F-ratio formulas, post-hoc tests, and effect size with eta-squared.

intermediate

Paired Samples t-Test

Learn how to conduct a paired samples t-test for pre/post designs and repeated measures, with formulas, worked examples, and APA reporting format.

beginner

Pearson Correlation

Learn how to calculate and interpret the Pearson correlation coefficient (r) to measure the strength and direction of linear relationships between two variables.

beginner

Simple Linear Regression

Master simple linear regression: learn how to predict a continuous outcome from one predictor variable, interpret slope, intercept, and R-squared values.

intermediate

Effect Size & Power

Effect Size

Learn what effect size is, why it matters more than p-values alone, and how to calculate and interpret Cohen's d, Hedges' g, and eta-squared for your research.

beginner

Sample Size Determination

Learn how to calculate the right sample size for your research study using power analysis, effect size estimates, and practical planning considerations.

intermediate

Statistical Power & Power Analysis

Learn what statistical power is, why 80% is the standard threshold, and how to conduct a power analysis to determine if your study can detect real effects.

intermediate

Reliability & Validity

Cronbach's Alpha

Understand Cronbach's alpha for measuring internal consistency reliability. Learn the formula, interpretation guidelines, and what to do when alpha is low.

beginner

Inter-Rater Reliability

Learn how to assess inter-rater reliability using Cohen's Kappa and ICC. Understand percent agreement, chance correction, and interpretation benchmarks.

intermediate