Statistical calculators

Static, shareable method pages backed by the zero-dependency StatLab engine.

Welch's t-test calculator

Run a Welch two-sample t-test for unequal variances, with t, degrees of freedom, p-value, effect size, confidence interval, and APA-ready language.

Compare two independent groups with a rank-based Mann-Whitney U test, including U, z, p-value, rank-biserial effect size, and Cliff’s delta.

Compare three or more group means with one-way ANOVA, effect sizes, and multiple-comparison follow-ups.

Run chi-square tests for independence or goodness-of-fit with expected counts, χ², p-value, and Cramér’s V.

Estimate Pearson correlation with r, confidence interval, p-value, and APA-ready reporting language.

Fit simple or multiple OLS regression with coefficients, standard errors, intervals, model fit, and residual diagnostics.

Estimate power or required sample size for common t-tests, correlations, proportions, ANOVA, regression, and survival designs.

Pool study-level effect sizes with random-effects meta-analysis, heterogeneity statistics, and prediction intervals.