Can anyone please advised me on calculating sample size using Gpower? I want to see the effect of an intervention( independent variable: 2groups) on mental health (continuous) of participants and I have considered baseline outcome measure as a covariate? How can I calculate the sample size in this case? Furthermore, my two secondary outcomes (both are in continuous scale) are also affected by intervention according to the previous literature. In such case, do I have to consider them as a covariate? I am confused on numerator df and don't know what to put in both of these instances?