The research topic is The effects of social media on young adults' mental health relating to depression.

Is my logic correct below? As part of our research, we are also identifying if there is an association between existing mental health issues affecting depression in young adults (greater/less). Our variables are social media (IV), depression (DV, and demographics (age/gender).

• The moderating variables of existing mental health or self-esteem issues can alter the effect of the independent variable, social media, on the dependent variable, depression, changing the effect component of the cause-and-effect relationship.
• The mediating variables of frequent use or time spent on social media link the independent and dependent variables, enabling the relationship to be understood.

What would be an example of a control variable for this research topic? The effects of social media on young adults' mental health relating to depression?