1. Center for Experimental Economics in Education, Shaanxi Normal University, Xi’an, Shaanxi, China
2. Department of Agriculgural and Applied Economics, Univeristy of Georgia, Athens, GA, USA
3. Rural Education Action Program, Freeman Spogli Institute for International Studies, Stanford University, Stanford, CA, USA
4. Graduate School of Education, Stanford University, Stanford, CA, USA
5. School of Advanced Agricultural Sciences, Peking University, Beijing, China