Free & open
Everything here is free, runs in your browser, and needs no sign-up. Look up a concept, run a quick calculation, or grab a clean dataset to practice on — then do the real work in Stratum.
Plain-language definitions, formulas, and how-to-read guidance — plus Stratum's exact conventions.
P-value, sample size, and effect size — exact answers, computed right in your browser.
Paste your numbers, get a box-and-whisker chart, and download it as PNG or SVG.
Clean, documented, openly-licensed (CC0) CSVs to learn, demo, and test with.
These resources cover the basics. Stratum is the native app for Mac & Windows that turns a CSV into reports, tests, and publication-ready charts — in clicks, not code.
Stratum