ABSTRACT
Development is a complex business. While this might be a challenge to commentators and scientists, it is above all a problem for politicians and civil servants, who have the difficult job of explaining such a complicated concept to the man or woman in the street. It is equally difficult to formulate policy and evaluate whether that policy leads to positive results. The latter causes researchers all kinds of headaches. After all, it is their task to throw extra light on the question of where and when aid is useful. The question of how such a question can be answered is key to this chapter.
