3 min read
Statistical significance explained without any maths
What the number actually claims, what it doesn't, and the four sentences you need to read a result honestly without ever computing anything.
Everything we have published on Statistical significance: guides, experiments and what we learned along the way.
13 articles
3 min read
What the number actually claims, what it doesn't, and the four sentences you need to read a result honestly without ever computing anything.
3 min read
Adding a third variant costs you a third of your sample and buys you a comparison you may not need. Three cases where it's worth it, and one very common case where it isn't.
3 min read
An even split gets you the fastest answer. An uneven one limits how many customers see a change you're not sure about. You can't have both.
3 min read
Stopping early, testing everything at once, no guardrail, changing the test mid-flight and treating a win as a fact. All five are avoidable.
4 min read
The honest answer has three inputs and no marketing spin. Here's how to calculate it for your own site, and what to do when the number comes back too big.
2 min read
Stop celebrating statistical noise. Learn which metrics actually matter, how to reach significance, attribute results cleanly and document every learning.
2 min read
Your A/B test came back flat? A tie isn't a failure. Learn how to read an inconclusive result, what to do next, and how to turn it into real learning.
2 min read
Testing more than two versions at once is tempting, but every extra variant splits your traffic. Learn when A/B/n pays off and when classic A/B wins.
2 min read
A poorly run A/B test is worse than no test at all: it gives you false confidence. Here are the most common mistakes that invalidate results and how to prevent them.
2 min read
Sample size quietly ruins more experiments than any other factor. Learn the three variables behind it and how to know if your A/B test can actually reach a conclusion.
2 min read
Stop too early and you crown false winners; run too long and you waste traffic. Learn how to set the right A/B test duration before you launch.
2 min read
P-value, confidence level and false winners explained in plain English. Learn to read what your A/B testing tool tells you and stop shipping fake wins.
2 min read
Learn the core A/B testing vocabulary: control, variant, hypothesis, significance and metrics, so you can launch reliable experiments from day one.