An Assessment of Alternative Structural Models of Philanthropic Behavior

Abstract

In this article, the question of whether differences in four structural models of charitable behavior make any difference to the findings regarding the major determinants of philanthropic contributions is addressed. Using data from Independent Sector’s Giving and Volunteering Survey, giving and volunteering equations using the standard Tobit model, the “Heckit” model, the Cragg model with uncorrelated errors, and the Cragg model with correlated errors are estimated. Results indicate that the generalized two-stage approaches are far superior to the standard Tobit model for both monetary donations and volunteer time. For monetary giving, parameter estimates of the second-stage contribution equations are similar across the three alternative two-stage methods and there is no evidence of correlation between the first- and second-stage error terms. Second-stage estimates for volunteering from the Heckit and Cragg models with correlated errors are also similar and offer compelling evidence of correlated error terms.