Descriptive Statistics Calculator

Which “average” should you report?

The mean is the arithmetic average and the one people expect — but a single huge value drags it upward. The median (the middle value) ignores that, which is why salaries and response times are usually reported as medians. When the mean and median are far apart, the data is skewed, and the median is the more honest headline.

Sample vs population standard deviation

If your numbers are a sample drawn from a bigger group — almost always the case — use the sample standard deviation (dividing by n−1). The population version (dividing by n) is only correct when you genuinely have every member of the group. Getting this wrong slightly understates the spread, which this tool shows both ways so you can pick deliberately.

How outliers are flagged

A value is flagged when it falls more than 1.5×IQR below Q1 or above Q3 — Tukey's fences, the same rule that draws the whiskers on a box plot. It is a prompt to investigate, not a licence to delete: an outlier is sometimes the most important row in the dataset.