The Diversification Paradox: Research Portfolio Evolution in UK Universities

Prevailing research policy narratives emphasise specialisation and prioritisation as routes to competitive advantage in resource-constrained systems. Yet our analysis of UK universities over the past 25 years shows a counterintuitive trend: institutions are broadening, not narrowing, their research portfolios. This applies to both large comprehensive universities and smaller, historically focused institutions, suggesting diversification has become the dominant institutional trajectory. The study addresses a core measurement challenge: how to define whether an institution is ‘specialist’ or ‘generalist’. Using journal articles with at least one UK-affiliated author indexed in the Web of Science Core Collection from 2001–2025, we construct a national benchmark. Institutional diversity indices are calculated, normalised against this benchmark, and examined longitudinally. The pilot focuses on variety and balance, excluding disparity to support scalable and transparent comparison. Findings show a system-wide increase in subject diversity. Specialist institutions, including those in agriculture and hygiene, have also diversified. Diversity rises with publication volume but plateaus above approximately 2,500 articles per year and is positively correlated with REF Grade Point Average. Highly specialised institutions show a bifurcated impact profile: some achieve very high normalised citation impact, while many fall below the UK average, with more volatile diversity scores year on year. These results raise policy questions about whether convergence toward greater diversity reflects deliberate institutional strategy or systemic pressures from assessment and funding incentives. The relative diversity indices developed here offer a practical tool for monitoring research portfolios, informing policy on specialisation, and guarding against unintended homogenisation in national research systems.