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statistical-significance.md

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+---
+id:
+aliases: []
+tags: []
+title: Statistical Significance
+---
+# Statistical Significance
+
+[Statistical significance - Wikipedia](https://en.wikipedia.org/wiki/Statistical_significance)
+In statistical hypothesis testing,
+a result has statistical significance
+when a result at least as "extreme"
+would be very infrequent if the null hypothesis were true.
+
+More precisely,
+a study's defined **significance level**, denoted by $\alpha$,
+is the probability of the study rejecting the null hypothesis,
+given that the null hypothesis is true;
+and the p-value of a result, $p$,
+is the probability of obtaining a result at least as extreme,
+given that the null hypothesis is true.
+The result is said to be statistically significant,
+by the standards of the study, when $p \leq \alpha$
+
+The significance level for a study
+is chosen before data collection,
+and is typically set to 5% or much lower--
+depending on the field of study.
+
+The [**null hypothesis**](https://en.wikipedia.org/wiki/Null_hypothesis)
+(often denoted $H_{0}$)
+is the claim that the effect being studied does not exist,
+or that no relationship exists
+between two sets of data or variables being analyzed.
+
+If the null hypothesis is true,
+any experimentally observed effect is due to chance alone.
+
+In research,
+the researcher develops an [**alternative hypothesis**](https://en.wikipedia.org/wiki/Alternative_hypothesis)
+(often denoted $H_{A}$ or $H_{1}$)
+which claims that an effect or relationship _does_ exist.