ABSTRACT
P-values and 95% confidence intervals are discussed in previous Chapters.
When looking at the difference between two mean values however, neither of these techniques tell us whether the size of this difference is practically meaningful.
This Chapter discusses the concept of effect size and how it can be useful.
A commonly used measure of effect size, Cohen’s d, is introduced and explained. An example of its calculation and interpretation is given with full step-by-step instructions.
