1 Erratum to: Qual Quant DOI 10.1007/s11135-016-0386-2

The original article was published without an acknowledgment section. The complete acknowledgment section is given below.

Acknowledgements

The authors acknowledge financial support from the National Natural Science Foundation of China (71403015, 71521002), the Beijing Natural Science Foundation (9162013), Joint Development Program of Beijing Municipal Commission of Education, the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry of China (20152132001), and the Excellent Young Scholars Research Fund of Beijing Institute of Technology (20142142005).