New research introduces a novel way to measure policy design quality — the Average Instrument Diversity (AID) index. This metric captures whether governments reuse old tools or develop creative solutions tailored to specific problems.

Data & Methods: Using original datasets, we analyze environmental policy portfolios from 21 OECD countries to test AID's validity and reliability.

Key Findings: Countries with more diverse policy instruments show significantly better environmental outcomes — a counterintuitive result that challenges conventional wisdom about constraints improving governance.

Why It Matters: The research reveals two crucial factors driving this "design quality": fewer institutional barriers AND well-equipped bureaucracies.