What this site is
A free library of statistics calculators, interactive tables and learning guides for students, teachers and researchers. It exists because most calculator sites give you an answer and nothing else. An answer you cannot check teaches you nothing.
How we work
- Every formula is shown, in both its population and sample forms where both exist.
- Every dataset calculator displays its intermediate working.
- Worked examples use small, checkable datasets, and every example on the site has been verified against the site's own calculation engine.
- Quartiles and percentiles use the linear-interpolation method (Excel's QUARTILE.INC / PERCENTILE.INC); where methods differ between textbooks, the page says so.
Privacy
Calculations run entirely in your browser. We do not receive, store or sell the numbers you enter. There is no server for them to go to.
Corrections
Found an error? A wrong number in an example, a formula typeset badly, a method described unclearly. Tell us through the contact address on this page's footer and we will fix it and note the fix.