Piotr Płatkowski is a lecturer at the Faculty of Management and Economics, Gdańsk University of Technology, Poland.Ewa Lechman is a Professor of Economics at the Faculty of Management and Economics, Gdańsk University of Technology, Poland.Javier Barbero Jiménez is a lecturer in the Department of Economic Analysis, Universidad Autónoma de Madrid, Spain.Margarita Billón Currás is an Associate Professor at the School of Economics and Business, Universidad Autónoma de Madrid, Spain.