P-value Calculator
Determine the P-value from Z-scores for hypothesis testing. Calculate statistical significance for left-tailed, right-tailed, and two-tailed tests.
Complete User Guide
Follow these steps to find your P-value:
Step 1: Enter your Z-score (the test statistic).
Step 2: Select the test type (Left-Tailed, Right-Tailed, or Two-Tailed).
Step 3: Click 'Calculate P-Value' to get the probability.
Step 4: Compare the result to your significance level (α, usually 0.05). If P ≤ α, your result is statistically significant.
The Mathematical Formula
p = P(Z < z) or P(Z > z)
The P-value represents the probability of observing a result as extreme as yours if the null hypothesis were true:
- **Left-Tailed**: P(Z < z) - **Right-Tailed**: P(Z > z) = 1 - P(Z < z) - **Two-Tailed**: 2 * (1 - P(Z < |z|))
Frequently Asked Questions
Calculate
Verified Precise
Secure 100% Free Precise