Background: The h-index has its popularity in the global scientific community. Despite the h-index being used as an indicator of individual research achievement (IRA), two main disadvantages have not been solved: (1) all coauthors contributing equally to article bylines and (2) the integer nature of the h-index making it difficult to differentiate the IRAs among entities. This article evaluated the most cited authors, institutes, and states in United States in ophthalmology in recent ten years using a proposed hx-index.
Methods: Authors who worked for departments of ophthalmology in United States were selected for identifying their IRAs in Pubmed Central(PMC) since 2010. Using the PubMed search engine, we conducted an observational study of citation analyses in affiliated research institutes and states of all authors who worked for departments of ophthalmology since 2010. A total of 18,289 published articles from 46,121 authors related to departments of ophthalmology from 50 states were analyzed. The bootstrapping method was applied with an estimated 95% confidence interval (CI) to distinguish the differences in IRAs among states and institutes. The x-index and the Kano model were complemental to the h-index for identifying the group IRA characteristics and rankings. A pyramid plot was used to illustrate the importance of the author-weighted scheme(AWS) used for evaluating IRAs in academics. The hx-index combined both advantages of h-/x-index was proposed to assess IRAs for each facility. A significant difference was identified by observing two bands of estimated 95% CIs that were not overlapped. Furthermore, we drew a choropleth map on Google Maps to visualize the differences of IRA among states.
Results: There is a significant rise over time in the number of publications. The top-ranking states in hx-index based on publications and citations were Massachusetts(42.28),California(39.24), and Massachusetts(42.28). If only the top 100 authors were included for calculating the median hx-index, the top three would be California(6.45), Massachusetts(3.97). and New York(3.07) with no significant difference found among these three using the bootstrapping method. The institute and author with the highest hx-index were Harvard Medical School(Massachusetts) and Felipe A Medeiros (California), respectively. We demonstrated that Dr. Medeiros from California published 213 articles in PMC and used the example to elucidate the importance of AWS when IRAs were assessed.
Conclusions: With an overall increase in publications in the field of ophthalmology, IRAs assessed by these (1) hx-index, (2)the bootstrapping method, and (3) AWS should be emphasized and promoted more in the future.