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P-value Calculator
Significance Probe
Advanced P-Value & Hypothesis Validation
About the P-value Calculator
Convert a test statistic into a p-value to decide whether a result is statistically significant.
How to use the P-value Calculator
- Enter the Test Statistic (Z/T) and, for a t-test, the Degrees of Freedom (df) (leave as 0 for a Z-test).
- Choose the significance level Ξ± and click One-Tailed Test or Two-Tailed Test.
- Press Calculate.
Formula and method
The p-value is the probability of seeing a result at least as extreme as the one observed if the null hypothesis is true. If p < Ξ±, the result is called statistically significant.
Worked example
A Z-score of 1.96 gives a two-tailed p-value of about 0.05.
Tips
- A small p-value is not proof. Consider effect size and study design.
- Choose one-tailed only if you predicted the direction beforehand.
Frequently Asked Questions
If there were no real effect, you would see a result this extreme only about 3% of the time.