Statistics calculators

Sample size, correlations, t and chi-square tests, reliability and effect size.

Tools in this category

How many responses you need to estimate a percentage or a mean, with finite population, design effect and…

Pearson’s r between two variables, with p value, confidence interval, regression line and scatter plot.

Sample and population deviation, variance and coefficient of variation.

Compare two means (independent or paired) or one mean with a value, with p value, confidence interval and…

How precise your survey is, given the sample you actually collected.

How many participants do you need? Work out sample size for a t test, correlation, ANOVA, proportions or…

Chi-square test for contingency tables and goodness of fit, with Cramér’s V, residuals, Yates’ correction…

Compare the means of three or more groups: ANOVA, equal-variance check, Tukey or Games-Howell, effect size…

Reliability of a scale or questionnaire: alpha with a confidence interval, omega, and which items improve or…

Non-parametric tests for ordinal or non-normal data: exact p values when possible, effect sizes and Dunn’s…

Least-squares line or plane with coefficients, intervals, prediction, assumption checks and fit and residual…

Effect size between two groups or before and after, with confidence intervals, plain-language equivalents…

Rank correlation between two variables, which detects monotonic relationships even if they are not straight…

The range the true mean is likely to fall in at your chosen confidence level.

Measure agreement between raters with Cohen’s kappa (unweighted and weighted) or the intraclass correlation…

Classification metrics from a confusion matrix.

Convert between Cohen’s d, r, eta squared, f, odds ratio and AUC to compare studies that report the effect…

How many standard deviations a value sits from the mean and which percentile it occupies.

Content validity from expert judge agreement, item by item.

Aimed at research projects, theses and instrument validation. Each test reports its statistic, the degrees of freedom and the associated p-value.

p-values are computed from the exact distributions (Student's t and chi-square), not from approximate lookup tables.