What does it mean when research findings have high effect size?

When research findings have a high effect size, it indicates a strong relationship or difference between the variables being studied. Effect size is a quantitative measure that reflects the magnitude of a phenomenon observed in the research. A high effect size suggests that the impact of the intervention or the strength of the association between variables is substantial, meaning that the results are not only statistically significant but also relevant in a practical sense.

In practical terms, a strong effect size can guide practitioners in making informed decisions based on robust evidence. It signifies that changes or interventions may lead to meaningful improvements in real-world settings, making it an essential consideration for evidence-informed practice. Therefore, a high effect size underscores the importance of the research findings and their potential application in practice, effectively adding value to the body of knowledge in the field.