P-Value Calculator (Normal)

Determine the statistical significance of your results.

Parameters

Z-Score

Test Type

Statistical Significance

P-Value0.05Strong evidence against null hypothesis

Confidence Level95.00%

P-Value Visualization (Shaded Area)

Overview

The p-value is the probability of obtaining test results at least as extreme as the results actually observed, under the assumption that the null hypothesis is correct. A small p-value (typically ≤ 0.05) indicates strong evidence against the null hypothesis.

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Pro Tips

Use 'Two-Tailed' if you want to detect an effect in either direction.
Use 'Left-Tailed' or 'Right-Tailed' if you are only interested in one specific direction.
Always report the actual p-value rather than just 'p < 0.05'.

Fun Facts

"The 0.05 threshold was popularized by Sir Ronald Fisher in 1925 as an 'easy-to-use' benchmark."
"A p-value is NOT the probability that the null hypothesis is true."
"In very large datasets, even tiny, practically insignificant effects can have very small p-values."

Formula: p = P(Z ≥ |z|) for two-tailed test

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