Modeling and Measuring Scale Attraction Effects : An Application to Charitable Donations

Charities seeking donations typically employ an “appeals scale,” a roster of suggested amounts presented to potential donors, along with an “Other” category. Yet little is known about how the amounts comprising appeals scales affect whether a donation is made and, if so, jointly exert “pull” on its magnitude. Availing of multi-year panel data and a field experiment, we develop a model accounting for individual level donation incidence, amount, and appeals scale attraction effects. The model incorporates heterogeneity across donors in both upward and downward scale point attraction, as well as in donation patterns (e.g., seasonality), and accommodates multiple operationalizations of internal and external referents to summarize the effects of prior donation history and scale points, respectively.Overall results suggest that scale points do exert substantial attraction effects; that these vary markedly across donors; that they are in fact referent-based effects; that donors are more easily persuaded to give less than more; and that, while all scale points exert pull, influence wanes with distance. The modeling framework applies not only in donation contexts, but whenever an ordered categorical scale is used to collect data regarding an underlying latent response