Measuring Progress Towards Environmental Sustainability: A Benefit of the Doubt Composite Index for OECD Countries

ABSTRACT Environmental sustainability has become a central priority on the global agenda amid climate urgency, biodiversity loss, and commitments under the 2030 Agenda. Economies face increasing pressure to adopt development models aligned with climate neutrality and ecological transition. In this context, robust and comparable measurement tools are essential to assess countries' environmental performance and support evidence‐based policymaking. This study introduces a composite index to evaluate environmental sustainability across the 38 OECD countries from 2015 to 2024, using the Benefit of the Doubt (BoD) methodology. The analysis focuses on environmentally related Sustainable Development Goals, providing a targeted assessment of advanced economies' commitments and outcomes. Unlike traditional indices with fixed weights, BoD assigns weights endogenously to maximise each country's relative performance, ensuring greater objectivity and accounting for structural differences. The approach identifies benchmark countries, reveals performance gaps, and tracks progress over time, offering a robust tool for monitoring and policy design.