Anderson–Darling normality calculator
Paste one sample and compare the statistic, p-value and QQ plot.
Normal QQ plot
Inspect departures from the line.
Ordered quantiles
| Order | Theoretical | Observed |
|---|---|---|
| Fill in the fields above — the result is computed on this page. | ||
How do I use this page?
- Paste values.
- Inspect the statistic and plot.
What this page does not do: The p-value is an approximation and does not validate independence or the sampling plan.
Further reading
Theory — what does the Anderson–Darling test check?
The calculator takes a single data sample and reports the test statistic, the p-value and a QQ plot against the fitted normal distribution. The Anderson–Darling test gives more weight to discrepancies in the tails of the distribution than simpler comparisons, so it better catches deviations at the extremes of the data. A small p-value means the sample is hard to reconcile with the fitted normal distribution — a signal the data may not be normal, not proof of any particular cause.
Frequently asked questions
What does a small p-value mean?
See also
A/B test calculator
Compare two proportions in an A/B test. Calculate conversion rates, difference, uplift, z score, p value and c
A/B test planning — sample size, MDE and duration
Plan a two-proportion experiment, estimate detectable effect and traffic duration.
ACF and PACF autocorrelation calculator
Calculate ACF and PACF across time-series lags. Review the chart, reference bounds and coefficient table.