Effect size

Statistical measure of the magnitude of a phenomenon This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these messages) This article may require cleanup to meet Wikipedia's quality standards. The specific problem is: Math notation uses different symbols to represent the same quantities in similar formulas. Please help improve this article if you can. (May 2011) (Learn how and when to remove this message) This article may be too technical for most readers to understand. Please help improve it to make it understandable to non-experts, without removing the technical details. (February 2014) (Learn how and when to remove this message) (Learn how and when to remove this message) In statistics, an effect size is a quantitative measure of the magnitude of a phenomenon. It can refer to the value of a statistic calculated from a sample of data, the value of one parameter for a hypothetical population, or the equation that operationalizes how statistics or parameters lead to the effect size value. Examples of effect sizes include the correlation between two variables, the regression coefficient in a regression, the