Perhaps the visualization is just better this way, but your question is at least an interesting one to think about. How would the shape of the curve change, and

Perhaps the visualization is just better this way, but your question is at least an interesting one to think about. How would the shape of the curve change, and might it suggest slightly different conclusions? For example, it seems to me the absolute income version would be steeper at low incomes, perhaps amplifying the perceived impact of things like a living wage or basic income on educational outcomes. (I'm talking mainly about the psychological impact of the curve's shape, not raw statistical truths.)