Hypothesis testing
t-tests
| Test | Use case |
|---|---|
| Independent samples t-test | Compare means between two groups |
| Paired samples t-test | Compare before/after measurements |
| One-sample t-test | Compare a sample mean to a known value |
| Welch’s t-test | Compare groups with unequal variances |
Chi-square tests
- Chi-square test of independence — test association between categorical variables
- Chi-square goodness of fit — test if data follows an expected distribution
ANOVA
- One-way ANOVA — compare means across 3+ groups
- Two-way ANOVA — test two factors and their interaction
- Tukey’s HSD — post-hoc pairwise comparisons after significant ANOVA
Non-parametric tests
| Test | Use case |
|---|---|
| Mann-Whitney U | Compare two independent groups (non-normal data) |
| Wilcoxon signed-rank | Compare paired observations (non-normal data) |
| Kruskal-Wallis | Compare 3+ groups (non-normal data) |
| Kolmogorov-Smirnov | Test if data follows a specific distribution |
| Shapiro-Wilk | Test for normality |
Regression analysis
Linear regression
Logistic regression
Multiple regression
Correlation
| Method | When to use |
|---|---|
| Pearson | Linear relationship between continuous variables |
| Spearman | Monotonic relationship, ordinal data, or non-normal distributions |
| Kendall | Small samples or many tied ranks |
| Point-biserial | Correlation between binary and continuous variables |
Effect size measures
The AI automatically reports effect sizes alongside p-values:- Cohen’s d — for t-tests (small: 0.2, medium: 0.5, large: 0.8)
- Eta-squared — for ANOVA (proportion of variance explained)
- Cramér’s V — for chi-square tests (association strength)
- R-squared — for regression (variance explained)