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Data & Analytics · Intermediate

P-Value

The probability, assuming the null hypothesis is true, of observing results at least as extreme as those in the sample.

Definition

If p ≤ α, reject H0. A small p-value indicates the data are unlikely under H0. It is not the probability that H0 is true, and it says nothing about effect size.

Example

p = 0.03 < α = 0.05, so reject H0.

Exam tip

A p-value is not P(H0 is true), and statistical significance is not practical significance.

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