Cohen's d effect size scale classifies an effect size of 0.5 as what?

Cohen's d is a measure used to determine the size of an effect, calculated as the difference between two means divided by the pooled standard deviation. The effect size classifications according to Cohen's conventions categorize the strength of the effect size as follows: an effect size of 0.2 is considered small, 0.5 is considered medium, and 0.8 is considered large.

Therefore, an effect size of 0.5 reflects a medium effect, indicating a moderate level of difference or association between the groups being compared. This categorization is widely used in research to provide a benchmark for interpreting the magnitude of differences in various studies, informing practitioners about the practical significance of findings beyond just statistical significance.