Leiden University

EXECUTIVE SUMMARY AND STRATEGIC VISION

Leiden University presents a robust scientific integrity profile, characterized by a low overall risk score (-0.149) that reflects strong governance and a commitment to quality. The institution demonstrates exceptional control over risks associated with publication channels and research fragmentation, significantly outperforming national averages in areas such as output in discontinued journals and redundant publications. However, areas of moderate risk emerge related to authorship patterns and impact dependency, specifically in hyper-authorship, hyperprolific authors, and the gap between total and institution-led research impact. These indicators, while not critical, suggest vulnerabilities that could challenge the University's mission. This profile of integrity underpins Leiden's academic prestige, which is evident in its outstanding performance in the SCImago Institutions Rankings, particularly in Pharmacology, Toxicology and Pharmaceutics (ranked 1st in the Netherlands), Biochemistry, Genetics and Molecular Biology (4th), and Medicine (5th). To fully align its operational practices with its stated mission of achieving "excellence in all its research" and fostering "critical assessment," it is recommended that the University proactively review its authorship and collaboration policies. By addressing these moderate-risk areas, Leiden can reinforce its position as a global leader, ensuring its significant academic impact is both sustainable and structurally sound.

ANALYSIS BY INDICATOR

Rate of Multiple Affiliations

With a Z-score of -0.412, Leiden University demonstrates a lower incidence of multiple affiliations compared to the national average of -0.033. This indicates a prudent and rigorous management of institutional representation. The University's approach effectively mitigates the risks associated with this practice, which, while often legitimate, can sometimes be used strategically to inflate institutional credit or engage in “affiliation shopping.” By maintaining a rate below the national standard, Leiden University reinforces the clarity and transparency of its collaborative contributions, ensuring that its institutional brand is associated with substantive partnerships rather than nominal affiliations.

Rate of Retracted Output

The institution's Z-score for retracted output is -0.324, which is statistically comparable to the national average of -0.277. This reflects a state of statistical normality, where the level of risk aligns with what is expected for its context and size. Retractions are complex events, and a low, stable rate suggests that the University's quality control and post-publication supervision mechanisms are functioning as intended. The data does not point to systemic failures in pre-publication review or a vulnerability in the institutional integrity culture, but rather indicates a responsible handling of scientific correction that is in sync with the national environment.

Rate of Institutional Self-Citation

Leiden University's institutional self-citation rate (Z-score: -0.282) is slightly more favorable than the national benchmark (Z-score: -0.383), but both are well within a low-risk range. This reflects a prudent profile, suggesting the institution manages its citation practices with slightly more rigor than the national standard. A certain level of self-citation is natural and reflects the continuity of research lines. The University's low score indicates a healthy balance, successfully avoiding the 'echo chambers' or scientific isolation that can arise from disproportionately high rates. This demonstrates that the institution's academic influence is validated by the broader global community, not just inflated by internal dynamics.

Rate of Output in Discontinued Journals

The University shows an exceptionally low rate of publication in discontinued journals, with a Z-score of -0.504, which is even lower than the already minimal national average of -0.494. This signifies a state of total operational silence regarding this risk. A high proportion of output in such journals would be a critical alert regarding due diligence in selecting dissemination channels. Leiden's near-zero incidence demonstrates a robust institutional awareness and effective information literacy, ensuring that research is channeled through reputable media that meet international ethical and quality standards, thereby protecting its reputation and resources from predatory or low-quality practices.

Rate of Hyper-Authored Output

The institution exhibits a Z-score of 1.143 for hyper-authored output, a figure notably higher than the national average of 0.843. This indicates a high exposure to this particular risk, suggesting the University is more prone to showing alert signals than its peers, even within a national context where this practice is somewhat common. While extensive author lists are legitimate in 'Big Science' collaborations, a high score outside these contexts can signal author list inflation, which dilutes individual accountability. This heightened rate warrants a review to distinguish between necessary massive collaborations and potential 'honorary' authorship practices that could compromise transparency.

Gap between Impact of total output and the impact of output with leadership

Leiden University's Z-score for the impact gap is 0.471, significantly higher than the national average of 0.085. This suggests a high exposure to dependency on external collaborations for impact, a pattern that is more pronounced at the institution than in the country as a whole. A wide positive gap, where overall impact is high but the impact of institution-led research is comparatively low, signals a potential sustainability risk. This finding invites reflection on whether the University's excellent metrics are a result of its own structural capacity or strategic positioning in collaborations where it does not exercise primary intellectual leadership, potentially making its perceived prestige dependent and exogenous.

Rate of Hyperprolific Authors

With a Z-score of 0.749, the University shows a higher rate of hyperprolific authors than the national average of 0.444. This indicates a high exposure to the risks associated with extreme individual publication volumes. While high productivity can reflect leadership in large consortia, rates exceeding the human capacity for meaningful intellectual contribution can point to imbalances between quantity and quality. This elevated score serves as an alert for potential risks such as coercive authorship, data fragmentation, or the assignment of authorship without real participation—dynamics that prioritize metric inflation over the integrity of the scientific record.

Rate of Output in Institutional Journals

The University's rate of publication in its own journals is minimal, with a Z-score of -0.268, which is consistent with the very low national average of -0.245. This reflects an integrity synchrony, where the institution is fully aligned with a national environment of maximum scientific security in this regard. Excessive dependence on in-house journals can raise conflicts of interest and risks of academic endogamy by bypassing independent external peer review. Leiden's negligible rate demonstrates a strong commitment to global visibility and competitive validation, ensuring its scientific output is assessed through standard, independent channels.

Rate of Redundant Output

Leiden University demonstrates a very low rate of redundant output, with a Z-score of -0.490, placing it in a more secure position than the national average (Z-score: -0.302, risk level: low). This signals a preventive isolation, where the institution does not replicate the low-level risk dynamics observed in its environment. A high rate of bibliographic overlap often indicates data fragmentation or 'salami slicing' to artificially inflate productivity. The University's exceptionally low score indicates strong editorial oversight and a research culture that prioritizes significant new knowledge over the volume of publications, thereby upholding the integrity of the scientific evidence base.