Resumen
In order to uncover cartels, screens can be a useful tool for competition authorities, using them to support opening an investigation or to filter industries prone to anticompetitive behaviour for further investigation. Screens can also help authorities to estimate the duration of the infringement, by identifying the starting point and the ending of the respective practice.This paper reviews the main screens identified in the empirical literature and also used by competition authorities in order to uncover firms? behaviours which are more likely to be consistent with collusion than with competition.