P-value Calculator
Calculate p-values for hypothesis testing using various statistical distributions. This tool supports Z-tests, T-tests, Chi-square tests, and F-tests to help you determine the statistical significance of your results.
How to Use the P-value Calculator
- Select the appropriate statistical distribution for your test
- Enter your calculated test statistic
- If required, enter the degrees of freedom for your test
- Click "Calculate P-value" to get your results
Understanding P-values
A p-value is the probability of obtaining test results at least as extreme as the observed results, assuming that the null hypothesis is true. Common significance levels are:
- p < 0.01: Very strong evidence against the null hypothesis
- p < 0.05: Strong evidence against the null hypothesis
- p < 0.10: Weak evidence against the null hypothesis
- p ≥ 0.10: Insufficient evidence to reject the null hypothesis
Distribution Types
- Z-distribution: Used for large sample sizes (n > 30) or when population standard deviation is known
- T-distribution: Used for small sample sizes when population standard deviation is unknown
- Chi-square distribution: Used for tests of independence and goodness of fit
- F-distribution: Used for ANOVA and comparing variances
Important Notes
Disclaimer: This calculator provides two-tailed p-values by default. For one-tailed tests, divide the result by 2. Always verify your statistical assumptions before interpreting results. This tool is for educational and research purposes only.