title: Collective philanthropy: describing and modeling the ecology of giving.
abstract: Reflective of income and wealth distributions, philanthropic gifting appears to follow an approximate power-law size distribution as measured by the size of gifts received by individual institutions. We explore the ecology of gifting by analysing data sets of individual gifts for a diverse group of institutions dedicated to education, medicine, art, public support, and religion. We find that the detailed forms of gift-size distributions differ across but are relatively constant within charity categories. We construct a model for how a donor's income affects their giving preferences in different charity categories, offering a mechanistic explanation for variations in institutional gift-size distributions. We discuss how knowledge of gift-sized distributions may be used to assess an institution's gift-giving profile, to help set fundraising goals, and to design an institution-specific giving pyramid.
authors.affiliation: Computational Story Lab, University of Vermont, Burlington, Vermont, United States of America.
authors.forename: William L
authors.initials: WL
authors.lastname: Gottesman
authors.affiliation: Department of Mathematics and Statistics, University of Vermont, Burlington, Vermont, United States of America; Center for Complex Systems, University of Vermont, Burlington, Vermont, United States of America; Computational Story Lab, University of Vermont, Burlington, Vermont, United States of America; Vermont Advanced Computing Core, University of Vermont, Burlington, Vermont, United States of America.
authors.forename: Andrew James
authors.initials: AJ
authors.lastname: Reagan
authors.affiliation: Department of Mathematics and Statistics, University of Vermont, Burlington, Vermont, United States of America; Center for Complex Systems, University of Vermont, Burlington, Vermont, United States of America; Computational Story Lab, University of Vermont, Burlington, Vermont, United States of America; Vermont Advanced Computing Core, University of Vermont, Burlington, Vermont, United States of America.
authors.forename: Peter Sheridan
authors.initials: PS
authors.lastname: Dodds
mesh_terms: D000533:Altruism; D006801:Humans; D007182:Income; D008962:Models, Theoretical