| Abstract -  
          This work presents an 
          empirical analysis of the economies of vertical integration in fixed 
          telecommunications, which is an issue of large interest but rarely 
          addressed from the empirical perspective. The dataset includes 
          European incumbent firms and the analysis employs a method based on 
          Data Envelopment Analysis. It allows to compute the economies of 
          vertical integration by comparing, for each firm, the efficiency 
          scores obtained with respect to the separated firms frontier with the 
          efficiency scores computed with respect to the integrated firms 
          frontier. The results show that diseconomies of vertical integration 
          are relevant, providing an important argument in favor of separation 
          policies. However, they reduce when the downstream output (retail 
          lines) is split in narrow and broadband lines (i.e., by considering 
          the quality of the downstream accesses), for firms more concentrated 
          on broadband. |