Definition: A statistic used to evaluate the outcome of a hypothesis test in Null Hypothesis Significance Testing (NHST). It refers to the probability of observing an effect, or more extreme effect, assuming the null hypothesis is true (Lakens, 2021b). The American Statistical Association’s statement on p-values (Wasserstein & Lazar, 2016) notes that p-values are not an indicator of the truth of the null hypothesis and instead defines p-values in this way: “Informally, a p-value is the probability under a specified statistical model that a statistical summary of the data (e.g., the sample mean difference between two compared groups) would be equal to or more extreme than its observed value” (p. 131).

Related terms: Null Hypothesis Statistical Testing (NHST), statistical significance

References: https://psyteachr.github.io/glossary/p.html, Lakens (2021b), & Wasserstein and Lazar (2016)

Drafted and Reviewed by: Alaa AlDoh, Flávio Azevedo, Jamie P. Cockcroft, Charlotte R. Pennington, Suzanne L. K. Stewart, Robbie C.M. van Aert, Marcel A.L.M. van Assen, Martin Vasilev

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