P-Value Calculator
Calculate the p-value from a test statistic to determine statistical significance.
P-Value
0.0124
One-tailed
0.0062
Two-tailed
0.0124
Significance at
α = 0.05Reject null hypothesis
α = 0.01Fail to reject null hypothesis
α = 0.001Fail to reject null hypothesis
Interpretation
Significant (p < 0.05)
What is a P-Value?
The p-value is the probability of obtaining results at least as extreme as the observed results, assuming the null hypothesis is true. A small p-value suggests the data is inconsistent with the null hypothesis.
Significance Levels
α = 0.05 is commonly used as the threshold. If p < α, we reject the null hypothesis. Fields like particle physics use much stricter thresholds (α = 0.0000003).
Correct Interpretation
The p-value is NOT the probability that the null hypothesis is true. It's the probability of the data given that the null hypothesis is true. Don't confuse it with practical significance.