Here are three reasons why you should ALWAYS report your estimates of the effect size:
- Your estimate of the effect size constitutes your study’s evidence. A p value might tell you the direction of an effect, but only the estimate will tell you how big it is.
- Reporting the effect size facilitates the interpretation of the substantive significance of a result. Without an estimate of the effect size, no meaningful interpretation can take place.
- Effect sizes can be used to quantitatively compare the results of studies done in different settings.