First Author:   Luisa Rosti University of Pavia lrosti@eco.unipv.it   Department of Political Economy and Quantitative Methods Pavia, Italy       Second Author: Chikara Yamaguchi Sapporo Gakuin University chikara@ma.0038.net   11 Bunkyo-dai Ebetsu, 069-8555, Japan       Third Author: Carolina Castagnetti University of Pavia castca@eco.unipv.it   Department of Political Economy and Quantitative Methods Pavia, Italy