According to Prof. Diakopoulos by accountability we mean the degree of which one decides when and how an algorithmic system should be guided (or restrained) in the risk of crucial or expensive errors, discrimination, unfair denials, or censorship. Simply put, we may say that holding a system accountable means we should control it at technical as well as at organizational level
(Book Chapter from 97 Things About Ethics Everyone in Data Science Should Know by Bill Franks, O'Reilly Media, Inc.).