It's the Effect Size, Stupid: What effect size is and why it is important, 2002

The paper offers a description on how to calculate effect size as well as how to interpret the results. It offers examples of practices to support claims. He argues that effect size can assist researchers and practitioners go beyond whether an intervention works to understand how large an impact will be if the practice is implemented in the field.

go to the website:  http://www.cemcentre.org/evidence-based-education/effect-size-resources