HKU Performance in ESI data – Research Performance Statistics Released in September 2023

1. Introduction to ESI data

Essential Science Indicators (ESI) data are statistical data that help identifying top-performing research and emerging areas of research in science and social sciences based on the Web of Science Core Collection data. ESI surveys more than 11,000 journals across 22 broad disciplines (Essential Science Indicators Help, 2023).

Based on the data released in September 2023, which covered a 10-year plus 6-month period (i.e. January 2013 to June 2023), we have analysed the research performance of The University of Hong Kong (HKU), which is home to a group of exceptionally talented scholars and researchers across a wide range of disciplines. Several significant findings are highlighted in the following paragraphs.

2. Distribution of Highly Cited Papers quantity in 2013-2022

Highly Cited Papers are the top one percent in each of the 22 ESI subject areas per year. Firstly, the number of papers cited at different levels of citation and construct distributions for each field and year are counted. Then, these distributions for each field/year are used to set selection thresholds by taking the same fraction of papers (ESI Highly Cited Papers, 2023). This procedure considers factors that citation rates vary by field and older papers are cited more than recent papers.

Figure 1 – Number of HKU Highly Cited Paper by Publication Year (2013-2022)

In the September 2023 release, a total of 1191 Highly Cited Papers were authored by researcher affiliated with HKU. The graph reveals the distribution of the papers by publication year, except 2023. Among the Highly Cited Papers by HKU authors, 64 were published in 2013 while 176 were published in 2022. A general upward trend of research papers recognised to be highly cited over the examined period can be observed.

3. HKU Highly Cited Papers in the 22 Research Fields

Among the 1191 Highly Cited Papers authored by HKU scholars, 28.63% were in Clinical Medicine, which is the highest, followed by 8.98% in Engineering and 7.98% in Social Science, General (Figure 2).

Figure 2 – Number of HKU Highly Cited Papers by Research Field

HKU scholars’ research was particularly influential in the fields of Microbiology, Immunology and Clinical Medicine in the recent 10 years (Table 1).

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And those received the highest number of citations in each research field are listed in the following table.

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4. HKU Hot Papers

Hot papers are papers published in the past two years that received a number of citations in the most recent two-month period that places them in the top 0.1% of papers in the same field.

Among a total of 39 hot papers authored by HKU scholars in 13 subject fields, 43.59% were in Clinical Medicine, followed by 7.69% in both Immunology and Engineering (Figure 3).

Figure 3 – Number of HKU Hot Papers by Research Field

HKU scholars’ research was particularly influential in the fields of Immunology, Microbiology, and Clinical Medicine in the recent 2 years (Table 3).

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5. Citation Ranking of HKU Research within ESI Research Fields

Citation ranking was calculated based on the citation counts of the publications in the covered period. The percentile was calculated by the rank of HKU in relation to total number of institutions in the field.

HKU ranked within the top 10% relative to international institutions in four disciplines – Clinical Medicine, Environment/Ecology, Engineering, and Social Science, General. Most notably, in Clinical Medicine, HKU outperformed 97% of other ranked institutions, Engineering, 96%, and Social Science, General, 96%.

These outstanding performances in these disciplines highlight the current strengths and areas of excellence of HKU.

Research FieldsRank of HKUTotal Number of Institutions [Note 1]Percentile [Note 2]
Clinical Medicine196599397
Social Sciences, General92210596
Materials Science183132286
Computer Science12674083
Table 4 – Ten HKU’s Best Performing ESI Disciplines

1) Total number of institutions is the number of institutions included in the ESI data, i.e., the top 1% of institutions received highest number of citations in a field (Essential Science Indicators: Librarian, 2023)
2) The Percentile transforms the rank into a percentile value. If Percentile is 97th, the number of citations received by institution is higher than that of 97% of all ranked institutions.  

6. Limitation and Conclusion

ESI data and rankings primarily rely on citations within a specific year-scope and databases, so the analysis above only gives a snapshot of the outstanding performance of HKU scholars.

Beyond simplistic quantitative metrics, the potential societal impact brought by HKU scholars’ quality research also worth noticing and appreciation. A few guidelines on the responsible use of metrics are also available on our LibGuide.

If you hope to know about the quality research and societal impact by HKU scholars, check-out the following posts:


Essential science indicators help. (2023).

ESI highly cited papers. (2023).

Essential Science Indicators: Librarian. (2023).