P-Value Calculator
Calculate the p-value from a z-score or t-statistic. Determine whether your hypothesis test result is statistically significant for one-tailed and two-tailed tests.
The p-value is the probability of obtaining a test statistic at least as extreme as the observed value, assuming the null hypothesis is true.
Interpretation:
- p < α: Reject the null hypothesis (statistically significant)
- p ≥ α: Fail to reject the null hypothesis
One-Tailed vs. Two-Tailed:
- Two-tailed: tests if the value differs in either direction
- Left-tailed: tests if the value is less than hypothesized
- Right-tailed: tests if the value is greater than hypothesized
Common α levels: 0.05 (5%), 0.01 (1%), 0.10 (10%)