Public Goods, Private Consumption, and Human Capital: Using Boosted Regression Trees to Model Volunteer Labour Supply

Abstract Economists use three types of models to describe volunteer labour supply: the public-goods model, the private-consumption model, and the human-capital model. We used data from an online survey questionnaire of volunteers working for the German Red Cross to study the extent to which utility components representing these three types help to explain volunteer labour supply. We analysed the survey data using boosted regression trees, where we controlled for several other potentially important socioeconomic correlates of volunteer labour supply. We used measures of relative influence and partial dependence plots to analyse the strength and the direction of the correlation of the utility components and the other socioeconomic variables with volunteer labour supply.