p-Value

The p-value is one of the most commonly used but also most frequently misunderstood concepts in statistical testing. At its core, it expresses how likely it would be to observe a result as extreme as the one obtained if the null hypothesis were true. A small p-value suggests that the data does not look very compatible with the null hypothesis, but it does not by itself indicate the size or practical importance of the effect. For that reason, p-values should always be interpreted together with effect size, sample size, and domain context.