What do effect sizes describe in research findings?

Effect sizes are a quantitative measure that reflect the magnitude of a difference between two groups or the strength of a relationship between variables. In the context of research findings, effect sizes specifically help to quantify how large or meaningful an observed effect is, beyond just determining whether the effect is statistically significant.

By calculating the effect size, researchers can understand the practical implications of their findings; for instance, they can gauge whether a treatment or intervention has a significant impact and how substantial that impact is in real-world terms. This measurement is crucial for making informed decisions based on research, as it provides insight into the extent of the change or difference, which can inform practice, policy, and future research directions.

Statistical significance, on the other hand, simply indicates whether the results are likely due to chance rather than a true effect, without measuring how large that effect is. Political context and strength of association, while important concepts in research, do not specifically address the quantitative magnitude of difference that effect sizes represent.