STATISTICAL COUNSEL FOR EXPERIMENTERS
Know, with confidence,
whether your test truly won.
Bring us your numbers. We attend to the mathematics.
No account · your data never leaves the page · every result shareable as a link
I · PLAN
Before the test
How many visitors you need, what your traffic can detect, and how long it will take.
II · ANALYZE
The verdict
Frequentist and Bayesian readings of your result, rendered side by side, in plain language.
III · DIAGNOSE
When in doubt
Health checks for a test that looks wrong — and study, for when you'd rather understand.
UNSURE WHERE TO BEGIN?
Two questions, and we'll seat you at the right table.
Help me chooseThe library
Essays on the statistics of experimentation, written for people who run tests — not for statisticians. With interactive charts.
PROBABILITY DISTRIBUTIONS, EXPLAINED →