Let's say I'm running an A/B test where I randomly select users to be in the control group (group A) or the treatment group (group B). I want to measure the impact of the treatment on the revenue per user for my video game. However, I know that some users are heavy gamers (20+ hours a week) while some users are very casual (< 3 hours a week). How can I control for this when estimating the impact of the treatment on revenue per user? As an extra note, the experiment has already started and the users have already been randomly selected into the groups.
I was thinking that I could run a linear regression model where the outcome is the revenue per user and the control variables would be a treatment indicator and the average hours played per week. Is this the right approach?