Editing Effect size (section)

===Standardized and unstandardized effect sizes===
The term ''effect size'' can refer to a standardized measure of effect (such as ''r'', [[Cohen's d|Cohen's ''d'']], or the [[odds ratio]]), or to an unstandardized measure (e.g., the difference between group means or the unstandardized regression coefficients). Standardized effect size measures are typically used when:
* the metrics of variables being studied do not have intrinsic meaning (e.g., a score on a personality test on an arbitrary scale),
* results from multiple studies are being combined,
* some or all of the studies use different scales, or
* it is desired to convey the size of an effect relative to the variability in the population.
In meta-analyses, standardized effect sizes are used as a common measure that can be calculated for different studies and then combined into an overall summary.