Collective Philanthropy: Describing and Modeling the Ecology of Giving

TL;DR

This paper analyzes the distribution of philanthropic gifts across various institutions, revealing category-specific patterns and proposing a model linking donor income to giving preferences, aiding fundraising strategies.

Contribution

It introduces a model explaining how donor income influences gift sizes across categories, enhancing understanding of giving ecology and aiding fundraising planning.

Findings

Gift-size distributions follow power-law patterns within categories.

Distributions vary across categories but are stable within them.

A model links donor income to gift preferences.

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.