First Author:   E. Roy Weintraub Duke University erw@econ.duke.edu         Second Author: Richard Watt Universidad Autónoma de Madrid richard.watt@uam.es   Dept. Análisis Económico, Fac. C.C.E.E., UAM,, Ctra. Colmenar, km. 15 Madrid, 28049, Spain   +34609404388(Phone) +34913978616(Fax) http://www.serci.org