Behavioural Types in Public Goods Games: A Re-Analysis by Hierarchical Clustering

We re-analyse participant behaviour in standard economics experiments studying voluntary contributions to a public good. Previous approaches were based in part on a priori models of decision-making, such as maximising personal earnings, or reciprocating the behaviour of others. Many participants however do not conform to one of these models exactly, requiring ad hoc adjustments to the theoretical baselines to identify them as belonging to a given behavioural type. We construct a typology of behaviour based on a similarity measure between strategies using hierarchical clustering analysis. We identify four clearly distinct behavioural types which together account for over 90% of participants in six experimental studies. The resulting type classification distinguishes behaviour across groups more consistently than previous approaches.