Statistical significance

Statistical significance is a judgment of whether a result occurs because of chance. When a result is statistically significant, we mean that it is unlikely that the result occurs because of chance or random fluctuation.

There is a cutoff for determining statistical significance. This cutoff is the significance level. If the probability of a result (the significance value) is less than the cutoff (the significance level), the result is judged to be statistically significant.

Statistical significance does not imply anything about the practical significance of a result. Furthermore, as the number of records increases, more results are statistically significant (less than the significance level) by chance. The effect size can account for these facts. The effect size helps determine whether a result has practical significance and is not influenced by the overall number of records (sample size).