Department of Statistics, Cracow University of Economics, 31-510 Cracow, Poland. kamil.fijorek@uek.krakow.pl|Department of Statistics, Cracow University of Economics, 31-510 Cracow, Poland. kamil.fijorek@uek.krakow.pl|Department of Statistics, Cracow University of Economics, 31-510 Cracow, Poland. kamil.fijorek@uek.krakow.pl|Department of Statistics, Cracow University of Economics, 31-510 Cracow, Poland. kamil.fijorek@uek.krakow.pl