A recent debate in the medical literature has arisen around the mortality effects of obesity. Whereas it has been argued that the obese die younger, the data that have become available do not immediately support this. This potentially undermines the hypothesis that modern life with its physical...

We estimate the effect of an increase in time cost on the return behavior of blood donors. Using data from the Australia Red Cross Blood Service, we ask what happens when pro-social behavior becomes more costly. Exploiting a natural variation in which donor wait times are random, we use the...