“…Several theoretical extensions of Baumol's model have been proposed, introducing the economies of scale (Schwarz, 1986), the international trade (Guccione and Gillen, 1990), the microfoundation of consumer demand in an imperfect competitive framework (Brunello and Scaramozzino, 1992), the role of investment in determining the dynamic equilibrium path and the role of intersectoral transfers in improving the employment performances of the economy (De Vincenti, 2000), the relationship between employment and output shares on the one hand and price and income elasticities on the other (Appelbaum and Schettkat, 2001). 5 A body of empirical research has been devoted to analyse productivity trends in services (Baumol et al ., 1985, 1989; Kendrick, 1985; Pellegrini, 1993; Boitani and Pellegrini, 1997; Mattey, 2001; Mohnen and ten Raa, 2001; Nordhaus, 2006) and final product productivity (Russo and Schettkat, 2001); to measure price and income elasticities of demand for goods and services (Summers, 1985; Borooah, 1987; Siracusano, 1990; De Vincenti et al ., 1999; Moller, 2001); to the employment benefits of having the right proportion between services and industry (Appelbaum and Schettkat, 1994; Sestito, 1997; Simonazzi and Villa, 1999). 6…”