What is effect size and how do I interpret it?

What is effect size and how do I interpret it?

Effect size is a quantitative measure of the magnitude of a phenomenon. It helps to understand the strength of a relationship or the size of a difference.

Can you give me an example of how to calculate effect size?

Sure! For example, if you're comparing two groups' means, you can use Cohen's d, which is calculated as the difference between the two means divided by the pooled standard deviation.

What does a small, medium, or large effect size mean?

A small effect size (around 0.2) indicates a weak relationship, a medium effect size (around 0.5) suggests a moderate relationship, and a large effect size (0.8 or higher) indicates a strong relationship.

How does effect size relate to statistical significance?

Effect size provides context to statistical significance. A statistically significant result may not always indicate a meaningful effect size, so both should be considered together.