How this calculator works
Estimate one-tailed or two-tailed p-values from a z-score for hypothesis testing.
Formula
p-value = 2 * (1 - Phi(|z|)) for two-tailed tests
Step-by-step
- Enter your z-score.
- Choose one-tailed or two-tailed test type.
- Calculate to get p-value and significance guidance.
Example
- z-score = 2.1
- Test type = two-tailed
p-value ≈ 0.0357
FAQs
What does p < 0.05 mean?
It typically indicates statistical significance at the 5% level.
Should I choose one-tailed or two-tailed?
Use one-tailed only for directional hypotheses defined before analysis; otherwise use two-tailed.