A standardized measure quantifies the magnitude of the difference between two group means. It expresses this difference in standard deviation units, providing a context-independent assessment of the practical significance of the observed effect. For instance, a value of 0.5 indicates that the means of the two groups differ by half a standard deviation.
This calculation is valuable in research syntheses, meta-analyses, and when comparing results across studies using different scales. It facilitates the comparison of treatment effectiveness, intervention impacts, or the magnitude of relationships, regardless of the original measurement units. Its use helps researchers to interpret the practical importance of findings beyond statistical significance, especially in fields where understanding the size of the impact is critical for informed decision-making. Its historical significance lies in its contribution to overcoming the limitations of solely relying on p-values, thus promoting a more nuanced understanding of research outcomes.
