Effect size for multiple regression?

#1
Hi would anyone be able to explain to me what measure should be used to estimate an effect size in multiple regression? I want to do a power calculation based on effect sizes from my pilot (multiple regression), but not sure what statistic to use? Thanks
 
#4
You should not use pilot data for determining effect size. These are almost certainly misleading.
https://statmodeling.stat.columbia....ity-experiment-not-estimate-treatment-effect/

The effect size in linear regression is usually Cohen's ƒ2, i.e. R²/(1-R²) .

With kind regards

Karabiner
Can I ask you also if you know what kind of statistic I should be looking at to see the effect sizes of individual predictors in a multiple regression?Thanks for your help.