P-Value Calculator

Calculate p-values for statistical tests (z-test, t-test, chi-square, F-test) with step-by-step solutions and distribution visualizations.

Calculator

Select a test type and enter the required values to calculate the p-value with step-by-step solutions.

Complete User Guide

What is a P-Value?

The p-value is the probability of observing a test statistic as extreme as, or more extreme than, the observed value under the null hypothesis. It helps determine statistical significance.

Common significance levels: α = 0.05 (5%), α = 0.01 (1%), α = 0.10 (10%)

Test Types

  • Z-Test: Used when population standard deviation is known
  • T-Test: Used when population standard deviation is unknown (requires degrees of freedom)
  • Chi-Square Test: Used for testing independence or goodness of fit
  • F-Test: Used for comparing variances or in ANOVA

Interpreting P-Values

  • p < 0.01: Very strong evidence against null hypothesis
  • p < 0.05: Strong evidence against null hypothesis (statistically significant)
  • p < 0.10: Weak evidence against null hypothesis
  • p ≥ 0.10: Little to no evidence against null hypothesis

Examples

Example 1: Z-Test

Z-Score: 1.96

Test Type: Two-Tailed

P-Value: ≈ 0.05

Example 2: T-Test

T-Score: 2.5

Degrees of Freedom: 10

Test Type: Two-Tailed

P-Value: ≈ 0.03

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