Early insights on the Emerging Sources Citation Index (ESCI): an overlay map-based bibliometric study

With rapid advances and diversifications in new fields of science and technology, new journals are emerging as a location for the exchange of research methods and findings in these burgeoning communities. These new journals are large in number and, in their early years, it is unclear how central these journals will be in the fields of science and technology. On one hand, these new journals offer valuable data sources for bibliometric scholars to understand and analyze emerging fields; on the other hand, how to identify important peer-reviewed journals remains a challenge-and one that is essential for funders, key opinion leaders, and evaluators to overcome. To fulfill growing demand, the Web of Science platform, as the world's most trusted research publication and citation index, launched the Emerging Sources Citation Index (ESCI) in November 2015 to extend the universe of journals already included in the Science Citation Index Expanded, the Social Sciences Citation Index, and the Arts & Humanities Citation Index. This paper profiles ESCI, drawing some comparisons against these three established indexes in terms of two questions: (1) Does ESCI cover more regional journals of significant importance and provide a more balanced distribution of journals? (2) Does ESCI offer earlier visibility of emerging fields and trends through upgraded science overlay maps? The results show that the ESCI has a positive effect on research assessment and it accelerates communication in the scientific community. However, ESCI brings little impact to promoting the inferior role of non-English countries and regions. In addition, medical science, education research, social sciences, and humanities are emerging fields in recent research, reflected by the lower proportion of traditional fundamental disciplines and applied science journals included in ESCI. Furthermore, balancing the selection of journals across different research domains to facilitate cross-disciplinary research still needs further effort.