Abstract (EN)

Managers in the fundraising and public sectors face the constant challenge of soliciting donations from a population who may or may not have donated before. Rather than merely asking respondents what they wish to donate, it is standard practice to present a set of suggested amounts – the appeals scale – in making donation requests. We study the relationship between what is requested and what is received by incorporating prior donation history into a comprehensive, ‘attraction’-based model of donation behavior. A large-scale field trial, coupled with a unique donation database from a French charity, allows measurement of several distinct appeals scale effects while accounting for underlying heterogeneity in donation behavior. A segment-level Bayesian model for the distribution of donations clarifies the influence of the appeals scale on donor behavior, as well the effect of ‘round’ scale values, such as those appearing on common bank notes. We find that the former effect can account for as much as 12% of overall donation behavior, the latter 7%, and moreover that these effects are essentially additive. Both effects, as well as proximity of scale points to a group-wise reference level, substantially alter the distribution of donations received. The data suggest that donations can be strongly influenced by choosing appropriate quantities to ask for, suggesting avenues for improving the practice of soliciting charitable requests.