There is currently an increasing shortage of organs available for transplantation. This is due to a reduction in traffic fatalities, the main provider of healthy organs, and an exploding demand from patients. An economist would say here that there is a classic case of rationing because the price is too low (at zero) and one should let patients pay for organs. But as this is viewed as unethical, we will have to live with rationing and waiting lists, unless one can bring more people to donate organs. This brings up the question why people donate, and in particular why there is altruism. This question is still puzzling, as altruism may emerge from a combination of sense of duty, coaxing, reciprocity, tradition, social pressure, and others.
Juan Cabasés and María Errea try to sort this out by focusing on blood and living organ donation. They model the decision process of the potential donor that in particular factors in some negative effect of donation. Then they administer a questionnaire and test their theory. The survey allows to highlight the attitude towards donating, which in theory corresponds in part to the degree of altruism. But it appears the perceived cost of donating is much more important, as well as information about the need for donations. This shows that in order to encourage more donations, information campaigns may be quite effective, and maybe rationing or a proper market would not be necessary.
Addendum: I forgot to mention a caveat the authors neglect: The survey is administered to staff of an university. Such employees, I believe, are more altruistic than average.