Statistical significance refers to the probability that, if, in the population from which this sample were drawn the true effect were 0 (or some hypothesized value) a test statistic as extreme or more extreme than the one gotten in the sample could have occurred.

In statistics, a number that expresses the probability that the result of a given experiment or study could have occurred purely by chance. This number can be a margin of error (“The results of this public opinion poll are accurate to five percent”), or it can indicate a confidence level (“If this experiment were repeated, there is a probability of ninety-five percent that our conclusions would be substantiated”).

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