Editing Statistical significance (section)

=== Effect size ===
{{Main|Effect size}}

Effect size is a measure of a study's practical significance.<ref name="A Visitor’s Guide to Effect Sizes"/> A statistically significant result may have a weak effect. To gauge the research significance of their result, researchers are encouraged to always report an [[effect size]] along with ''p''-values. An effect size measure quantifies the strength of an effect, such as the distance between two means in units of standard deviation (cf. [[Cohen's d]]), the [[Pearson product-moment correlation coefficient|correlation coefficient]] between two variables or [[Coefficient of determination|its square]], and other measures.<ref name=Pedhazur>{{cite book | last1 = Pedhazur | first1 = Elazar J. | last2=Schmelkin|first2=Liora P. | title = Measurement, Design, and Analysis: An Integrated Approach| edition=Student|publisher = Psychology Press |location = New York, NY | year = 1991|isbn =978-0-8058-1063-9 |pages=180–210}}</ref>