The economics of vocation or 'why is a badly paid nurse a good nurse'?

Given the longstanding shortage of nurses in many jurisdictions, why could not nursing wages be raised to attract more people into the profession? We tell a story in which the status of nursing as a 'vocation' implies that increasing wages reduces the average quality of applicants attracted. The underlying mechanism accords with the notion that increasing wages might attract the 'wrong sort' of people into the profession and highlights an (in)efficiency wage mechanism, particular to vocations, which makes wages sticky up wards. The analysis has implications for job design in vocation-based sectors such as nursing and teaching.