What is effect size and why is it important in research?

What is effect size and why is it important in research?

Effect size is a quantitative measure of the magnitude of a phenomenon. It's important because it helps researchers understand the practical significance of their findings, beyond just statistical significance.

Can you give me an example of effect size?

Sure! For instance, in a study comparing two teaching methods, if the average test scores of students using method A are 10 points higher than those using method B, the effect size quantifies that difference.

How do I calculate effect size?

Effect size can be calculated using various methods, such as Cohen's d for comparing two means or Pearson's r for correlation. The formula for Cohen's d is the difference between the two means divided by the pooled standard deviation.

What is considered a large effect size?

Generally, a Cohen's d of 0.8 or higher is considered a large effect size, indicating a strong relationship or difference.