Control is the least liked and the most controversial tasks of effective management. But if quality is important, there shouldn’t be any need for discussion regarding the need to control. But the „HOW“ should indeed be discussed – and is especially important in regards to performance, motivation and corporate culture. The key principle must therefore be the necessary minimum instead of the possible maximum. Where measuring, in the narrower sense of the word, isn’t possible, it must at least be possible to assess.