p-Value Calculator (One-Proportion z-Test)
Test whether a sample proportion differs from a baseline — z statistic, one/two-sided p-value, and a plain-language decision.
Also available in 한국어
- Test statistic z
- 1.6000
- Decision at 5% level
- Fail to reject
How it was calculated
- 1.601Test statistic z
z = (p̂ − p0) / √(p0(1−p0)/n) = (0.58 − 0.5) / 0.050000
Basis: One-proportion z-test (large-sample normal approximation)
- 10.96%02p-value = 0.10960 (10.9599%)
2 × (1 − Φ(|z|)) = 2 × (1 − Φ(1.6000))
Basis: Standard normal CDF Φ — alternative hypothesis Two-sided: p ≠ p0
- 03Significance decision (α = 5%)
p ≥ 0.05 → fail to reject the null — the observed difference is within chance
Basis: Significance level α = 0.05 (0.01/0.10 depending on the study)
- 04Interpretation caveat
The p-value is not 'the probability the null is true' but 'the probability of a result at least this extreme under the null'. Large samples make trivial differences significant — check effect size too
Reference simulation only, not tax advice. Verify with official sources before filing or paying.