Computed with standard statistical methods in your browser.
For z we use the normal distribution, for t the Student’s t distribution (via the regularized incomplete beta), and for chi-square the upper-tail gamma function. Choose one- or two-tailed for z and t.
Run the rest of your analysis with our other free stats tools.
The probability of seeing a result at least as extreme as yours if the null hypothesis is true.
Statistically significant at the 5% level — strong enough evidence to reject the null hypothesis.
Use t for small samples or unknown population variance; enter the degrees of freedom.
Chi-square tests use the upper tail, so the p-value is one-tailed by nature.
They use accurate numerical methods that match standard statistical software closely.