Mariusz Górajski University of Lodz   University of Lodz Department of Econometrics Narutowicza 65 Lodz, Lodz 90-131 Poland   mariusz.gorajski@uni.lodz.pl   http://www.katek.uni.lodz.pl/           JEL Areas: C4 : Econometric and Statistical Methods: Special Topics C0 : Mathematical and Quantitative Methods: General