Toward an Understanding of the Economics of Charity: Evidence from a Field Experiment
通过上门募捐的田野实验，研究彩票激励和募捐者外貌吸引力对捐款的影响，发现彩票能显著提高捐款额，且募捐者外貌吸引力的效果与彩票激励相当。
"This study develops theory and uses a door-to-door fundraising field experiment to explore the economics of charity. We approached nearly 5000 households, randomly divided into four experimental treatments, to shed light on key issues on the demand side of charitable fundraising. Empirical results are in line with our theory: in gross terms, our lottery treatments raised considerably more money than our voluntary contributions treatments. Interestingly, we find that a one standard deviation increase in female solicitor physical attractiveness is similar to that of the lottery incentive, the magnitude of the estimated difference in gifts is roughly equivalent to the treatment effect of moving from our theoretically most attractive approach (lotteries) to our least attractive approach (voluntary contributions)"--National Bureau of Economic Research web site.