" Opaque and invisible models are the rule, and clear ones very much the exception. We’re modeled as shoppers and couch potatoes, as patients and loan applicants, and very little of this do we see—even in applications we happily sign up for. Even when such models behave themselves, opacity can lead to a feeling of unfairness. "

― Cathy O'Neil , Weapons of Math Destruction: How Big Data Increases Inequality and Threatens Democracy