Time is Money: Choosing between Charitable Activities
研究了货币捐赠的税收优惠如何影响人们同时捐赠金钱和时间的决策，发现两者是替代品，但税收优惠对时间捐赠有正向溢出效应，最终使两者总体正相关。
This paper analyzes the impact of a preferential tax-price for monetary donations on the joint decision to donate time (volunteer) and money. The methodological approach takes into account that consumption of each charitable good affects consumption of the other. Using data from a national survey on household charitable giving, the results show that donations of time and money are substitutes. However, a decrease in the tax-price of monetary donations also has a positive effect on donations of time that acts outside the change in relative prices. This more than offsets the substitution effect leading to an overall positive correlation between the two charitable goods.