You quoted the part about controlling for age, then described the sort of mistake that comes from not controlling for age. So I would like to know what you think it means, in order to meet you where you are. I'm not expressing aggression toward you.
> So if I just assign the majority label to all of the population of a given demographics group, I would get the same result right? i.e., predicting "left" for all minorities under 30. You would also get ~70% accuracy.
I meant that even if you control age, gender, ethnicity, a very trivial predictor (i.e., always predicting the majority label) could yield similar performance. What I meant to say was that their model may not perform as well as they made it sound.