The missing effect of investments of firms in information and communication technologies on productivity is studied by various recent papers (e.g. Oliner and Sichels 1994, Landauer 1995, Brynjolfsson and Hitt 1996). Several explanations are given for this missing link. Our paper deals with two...

R&D expenditures of firms varies vastly between and within industries. In recent years a lot of theoretical and empirical studies attempted to explain the distribution of R&D expenditures. Four main factors repeatedly appeared in this literature: Firm size, market power, appropriability and...