📊 Statistics Calculator

P-Value Calculator

Calculate the p-value for hypothesis testing from a z-score or t-statistic — one-tailed and two-tailed — with significance interpretation at α = 0.05, 0.01, and 0.001.

Input Parameters

Enter a test statistic above
P-value = probability of results at least as extreme as observed, if H₀ is true.

P-Value Significance Levels

P-valueInterpretation
p > 0.05Not significant
p ≤ 0.05Significant (*)
p ≤ 0.01Very significant (**)
p ≤ 0.001Highly significant (***)

Frequently Asked Questions

What is a p-value?
The p-value is the probability of obtaining results at least as extreme as the observed ones, assuming the null hypothesis (H₀) is true. A small p-value (e.g. < 0.05) suggests the result is unlikely to be due to chance.
Two-tailed vs one-tailed test?
A two-tailed test checks if the effect is in either direction (≠). A one-tailed test checks for an effect in a specific direction only (> or <). Two-tailed tests are more conservative and generally preferred unless you have a directional hypothesis.

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