“…As in general an unrestricted form, such as equation 1, has been found to approximate the production structure better than the restricted forms, in this paper no attempt is being made to test the restrictions. 7 For instance, see Yuhn and Kwon (2000), Truett and Truett (1998), Burney and Al-Matrouk (1996), Wang (1995), Rushdi (1991), Apostolakis (1990), Supavud (1987), Iqbal (1986), Murthy (1986), Nelson (1985), Hunt (1984), Westoby and Guire (1984), Harper and Field (1983), Turnovsky et al . (1982), Williams and Laumas (1981), Halvorsen (1977), and Berndt and Christensen (1973).…”