Statistical assumptions checker
Paste one numeric sample to inspect normality, shape and possible outliers in one report.
Normal QQ plot
Points close to the reference line are consistent with a normal shape.
Diagnostic tests
| Test | Statistic | p-value |
|---|---|---|
| Fill in the fields above — the result is computed on this page. | ||
How to use this page
- Paste the observations.
- Inspect the QQ plot and outliers.
- Use the test selector if assumptions are doubtful.
What this page does not do: The Shapiro result is a documented Shapiro–Francia large-sample approximation. Results can be unstable for very small samples and overly sensitive for large samples.
Further reading
Assumption checks support a decision about a model; they do not replace inspection of the data and study design. The report combines a normal-score approximation, Anderson–Darling, a QQ plot, skewness, kurtosis and the IQR rule.
Frequently asked questions
Does p > 0.05 prove normality?
No. It means the sample did not provide strong evidence against the model.
Should every outlier be removed?
No. Verify measurement and context first.
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.