P-value Calculator
Please provide any one value below to compute p-value from z-score or vice versa for a normal distribution.
What is a p-value?
A p-value, or probability value, is a number describing how likely it is that your data would have occurred under the null hypothesis of your statistical test. In statistical hypothesis testing, the null hypothesis is a general statement or default position that there is no relationship between two measured phenomena, or no association among groups. The p-value helps you determine the significance of your results in relation to the null hypothesis.
The p-value is a number between 0 and 1, interpreted as follows: A small p-value (typically ≤ 0.05) indicates strong evidence against the null hypothesis, so you reject the null hypothesis. A large p-value (> 0.05) indicates weak evidence against the null hypothesis, so you fail to reject the null hypothesis. P-values very close to the cutoff (0.05) are considered to be marginal (could go either way). Always report the p-value so your readers can draw their own conclusions.
For normal distributions, a Z-score table can be used to determine p-values. This calculator uses the standard normal distribution to compute p-values from Z-scores and vice versa.