Convert a z-statistic into a p-value for hypothesis testing, with a clear interpretation of statistical significance at common thresholds.
How it works
- Input the calculated Z-statistic from your test.
- Select whether your hypothesis is one-tailed (left/right) or two-tailed.
- The system evaluates normal distribution probability to extract the P-value significance.
Frequently asked questions
What is statistical significance?
By convention, p < 0.05 is considered statistically significant — there is less than a 5% chance the result is due to random variation under the null hypothesis.
One-tailed vs two-tailed?
Use two-tailed when testing for any difference (higher or lower). Use one-tailed when you specifically predict the direction of the effect.
Does a low p-value prove my hypothesis?
No — it only provides evidence against the null hypothesis. It does not measure effect size or practical importance, and is often misinterpreted.