Seventh, individual delays and individual notice periods are normally deducted in the computation of the score for additional delays in the case of collective dismissals, when the latter do not add up to individual delays but run simultaneously or substitute for individual notice periods. Applying rigorously this principle resulted in a number of significant revisions (notably in Sweden, where the score fell from 6 to 1). Finally, and perhaps more important, the revised scores take much more systematically into account national or branch collective agreements and, where relevant, court rulings. This is due to the fact that, from a quantitative point of view, they can be easily measured. The seminal work of Lazear (1990) used severance pay and notice periods at ten years of job tenure. However, the tenure profile of severance pay and notice periods also matters, with progressive profiles typically considered as providing better incentives for workers’ investments in their job and having a less negative impact on firm experimentation and hiring (e.g. Blanchard and Tirole, 2003, Pries and Rogerson, 2005, Andres et al.,