In a hierarchy, every employee tends to rise to her or his level of incompetence – and stick there. Laurence Peter, the Canadian educational psychologist, introduced this concept in the 1960s as a humorous observation but it has since become a serious contribution to management science (like Parkinson’s law). The Peter Principle deals mainly with the experience of men, as might be expected, but see the related Paula principle for women. It is perhaps most applicable where people are promoted out of a specialist job they are good at (like sales, car mechanics or teaching) into a management position which usually requires a different set of skills, and for which they have received no training.