1. Department of Statistics and Econometrics, Bucharest University of Economic Studies, Bucharest, Romania
2. Department of Statistics and Econometrics, Bucharest University of Economic Studies, Bucharest, Romania; Institute of National Economy – Romanian Academy, Bucharest, Romania
3. Department of Statistics and Econometrics, Bucharest University of Economic Studies, Bucharest, Romania; National Scientific Research Institute for Labour and Social Protection, Bucharest, Romania
4. Department of Economics and Economic Policy, Bucharest University of Economic Studies, Bucharest, Romania
5. Department of Econometrics, University of Economics Prague, Prague, Czech Republic