The continuing evolution of the Highly Cited Researchers list — to promote fairness, accuracy, and research integrity
Explore the evolving methodology behind the Highly Cited Researchers list from Clarivate, focusing on the rise in exclusions due to unethical publication practices and the impact on global research integrity.
Across Clarivate, our focus is on protecting research integrity and providing trustworthy data, metrics and insights through rigorous selection, thoughtful curation and expert analysis. These efforts extend to our Highly Cited Researchers program. Since 2001, this program has recognized and celebrated individuals who have demonstrated significant and broad influence in their fields of research.
In response to the evolving research landscape, we have adapted our methodology to consider research quality and the nature of peer recognition alongside citation impact. We look for recognition via citations from a wide-ranging international network of citing authors. This ensures that we focus on individuals whose influence is significant and far-reaching.
Identification of Highly Cited Researchers begins with a quantitative algorithmic step, creating a longlist of candidates. This is followed by a qualitative screening process to create the final list. In recent years, the number of researchers excluded from the Highly Cited Researchers list at the qualitative stage has risen dramatically, with ~300 researchers or 4.5% of candidates excluded in 2021. By 2024, this skyrocketed to ~2,000 (23%).
This raises important questions about publication norms, research integrity and the evolving nature of scientific publishing. Why are so many researchers being excluded from this program? The answer lies in changes in research culture, the rise of anomalous and even unethical publication and citation practices and the increasing influence of new technologies – both for the facilitation of fraudulent activities and for detecting them.
The changing landscape of publication and citation behavior
The global research ecosystem has evolved significantly, and we have evolved our evaluation and selection methodology to reflect these conditions:
- The businessification of science: Individuals and institutions face intense competition and pressure to secure funding. This often leads to perverse incentives that reward quantity over quality.
- Challenges of evolving publishing models: While open access publishing has democratized access to scientific literature, and many publishers operate excellent open access editorial standards, the APC model creates a direct link between publication volume and revenue — creating opportunities for bad actors to exploit the system.
- Technological advancements: New and emerging technologies have supercharged the ability of fraudsters and opportunists to generate fake papers and to manipulate citation counts, while also improving detection methods for publishers, selective bibliometric databases and independent sleuths.
- Authorship marketplaces: Social media has facilitated interactions between researchers who are willing to pay for co-authorship and those willing to sell it.
These factors contribute to increased ‘pollution’ in the literature, often facilitated by fraudulent enterprises such as papermills. To ensure the integrity of our data, Clarivate has strengthened its filtering processes and product offerings across the portfolio — to make sure our data in the Web of Science remains of the highest quality and our selection of Highly Cited Researchers is based on robust analysis of our rigorously selected dataset. This is a high-stakes recognition program, providing metrics that have powered the Academic Ranking of World Universities for more than two decades. Such global rankings provide opportunities and international prestige for both researchers and their institutions.
Selection and evaluation to filter out manipulation
To uphold research integrity, our analysts employ both qualitative and quantitative filters to identify patterns of anomalous behaviour. Some of these patterns may reveal attempts to artificially inflate impact and stature.
Our evaluation and selection strategy is not one-dimensional; the process is complex and determined by combining the inter-related quantitative and qualitative information available to us. We specifically look for activity to strategically inflate the volume of publications and/or the volume of citations to papers. When one or more of these indicators appear in an individual’s profile, it may constitute sufficient evidence for exclusion:
- Excessive self-citation to boost personal citation count
- Strategic co-authorship or group citation rings: researchers who repeatedly cite one another, identified by analysis of unusual and anomalous sources of citations at the national, institutional, journal, and individual level
- Hyper-authorship: Publishing unusually high volume of papers respective to field norms
- External evidence of breaches in research integrity. Any and all papers by an author with a documented history of research misconduct, for retractions based on fraud, fabrication, plagiarism, image manipulation, fake peer review, and others, whether these have involved highly cited papers or less cited publications.
Clarivate seeks to recognize only those who adhere to accepted norms of scientific practice and research integrity, those who genuinely contribute to the advancement of the field, rather than those who may appear to exploit publication and citation metrics for personal gain.
The global impact of researcher exclusions
A deeper analysis of the list provides insights into global research and innovation trends along with shifting publication and scholarly trends. No two countries or regions are identical — we regularly see changing patterns and witness different cultural standards in terms of behaviours and activities.
Clarivate selects Highly Cited Researchers (HCRs) who have demonstrated significant field influence at an international, often global level, rather than local or regional impact. Our goal is to recognize world-class contributions.
Our 2024 program analysis reveals that some countries and regions exhibit higher exclusion ratios than others. The United States and mainland China stand out as the leading homes to Highly Cited Researchers. The U.S has consistently held the top position, while mainland China has seen rapid growth in recent years and now occupies second position. Mainland China is a prime example of a large, fast-growing research economy with some specific challenges that its government has acknowledged and recently taken steps to address following investigations into research misconduct. Mainland China, in common with some other Asian countries, also displays characteristic patterns of publication and citation aligned to seniority-conferred authorship (rather than active participation) which can result in a record of hyper-authorship. Additionally, its publication and citation networks enhance local rather than global citation patterns . At first glance, these trends can make it challenging to identify researchers with significant and broad impact, beyond national or regional impact.
Figure 1: Shaded areas represent the country distribution across the two axes (kernel density estimate), where darker areas represent a higher concentration of countries. The diagonal dotted line represents parity between the number of awards and exclusions per 100k researchers, based on the number of Web of Science researcher profiles. Points above this line represent regions with more awards than exclusions; points below the line indicate regions with more exclusions than awards. The horizontal dashed line represents the global median for HCR awards and the vertical dashed line the global median for exclusions.
All countries, other than the United States and mainland China are represented in the shaded area at the bottom left corner of the graph. The United States and mainland China are the leading locations for Highly Cited Researchers and can be seen as outliers on the graph. Both the U.S. and mainland China can be seen above the diagonal line, although mainland China is closer due to its higher proportion of excluded to included researchers.
Figure 2: Percentage of excluded researchers by ESI category.
Field-specific exclusion trends
The field categories in Highly Cited Researchers align with Essential Science Indicators, covering broad fields such as Materials Science, Molecular Biology and Genetics, Engineering, along with the Cross-field category introduced in 2018.
In 2024, 2,045 unique individuals were excluded — 1,177 from Cross-field and 868 from the other ESI categories. Exclusion rates vary significantly by discipline — Engineering has the highest (8.9%), while just one researcher was excluded from the Space Science category. In 2023, Mathematics was removed because we saw evidence of substantial publication and citation manipulation that overshadowed truly influential researchers. Given its relatively low publication and citation rates and fractionated topical focus, even a small increase in activity in certain niche areas could overwhelm and obscure other topics and investigators. A different approach is required for such disciplines, something we and others are actively exploring.
Clarivate remains committed to refining its stringent qualitative filters to maintain the validity of our list. We encourage the research community to contribute their suggestions to improve the Highly Cited Researchers selection process for 2025 and beyond, as we appreciate those who have provided valuable past contributions.
Conclusion
The rise in excluded individuals from the Highly Cited Researchers list is yet another cautionary sign for academia, industry, and governments. As research and publication practices evolve, including ever more sophisticated forms of gaming and fraudulent behavior, so too must the mechanisms we develop and deploy to promote fairness, accuracy and integrity.
For researchers and institutions alike, our message is clear – genuine impact and influence are what truly matter. Our ongoing commitment to research integrity seeks to ensure that the Highly Cited Researcher program remains a trusted benchmark for excellence.
Find out more about Highly Cited Researchers.
