In this paper we analyse, from a theoretical perspective, the effects of some of the initiatives implemented in Spain aimed at improving the scientific output in the Spanish Universities. Our results show that those incentives that represent a reduction of the teaching-hours or that represent an increase in the fixed-salary of professors can have little success on scientific output if: i) the distribution of abilities among professors, ii) the possibility that professors participate in the process of hiring new professors and, iii) the difficulties of university managers in monitoring the efforts that are expected to be devoted to research activities –as opposed to time devoted to private activities- by professors, are not considered. Additionally, the model allows us to offer an explanation to the observed fact in Spain that scientific output –in top-quality economic journals- is concentrate in a few Universities (Departments of Economics or Research Centres in Economics).
