“…There are a number of empirical studies, with mixed results. These report the existence of substitutability, which ranges from very low (Pitelis, 1987a(Pitelis, , 1997Poterba, 1987Poterba, , 1991 to moderate (Feldstein and Fane, 1973) and high (Feldstein, 1973;Koskela and Viren, 1984). 6 (Ultra) Rationality 383 © Blackwell Publishing Ltd and The Victoria University of Manchester, 2004.…”