P-Value

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Calculate

Example: a test gave a statistic z = 2.1. If the null hypothesis were true, what is the chance of a result as extreme as that? Change the values to work out your own case.

Observed statistic z Type of test Significance α (%)

Step by step

What each term means

P-Value: A number between 0 and 1: how surprising the result would be if there were no effect at all. Small means surprising; it doesn't mean a large effect.
As Extreme or More: The area of the tails beyond the observed value. In a two-sided test both sides count; in a one-sided test, only the side of the alternative hypothesis.
Given That H₀ Is True: The whole calculation assumes the null hypothesis. That is why the p-value is not the chance that H₀ is true: it is the chance of the data, assuming H₀.