Comparing public investments across sectors with CBA-based impact information and participatory budget choices

This paper proposes a hybrid decision-support framework that integrates cost–benefit analysis (CBA) with participatory budgeting (PB) to inform public-sector portfolio choices. To highlight the approach, we assume that CBA has been conducted to evaluate twelve independent infrastructure and service projects, establishing their economic viability. Subsequently, PB is employed to elicit community preferences regarding the same projects, ensuring alignment with public values. The combined framework aims to reconcile technical efficiency, understood here as welfare-economic appraisal implemented through standard modelling and valuation conventions, with democratic legitimacy, captured through direct, budget-constrained citizen prioritisation. Our findings show that respondents gave the strongest average support to health care and utilities projects, with education also performing relatively well, while public transportation and road infrastructure were preferred to transport-electrification initiatives. In contrast, public projects associated with private vehicle and freight vehicle electrification attracted comparatively weak support, and public transportation electrification was supported less strongly than conventional public transport investment. More broadly, respondents tended to favour projects that delivered larger consumer-surplus and environmental benefits and projects located in, or relevant to, their own area.