key: cord-0015696-pzdmq2ef authors: Yeh, Yu-Tsen; Chien, Tsair-Wei; Kan, Wei-Chih; Kuo, Shu-Chun title: The Use of hx-index to compare research achievements for ophthalmology authors in Mainland China, Hong Kong, and Taiwan since 2010 date: 2021-02-26 journal: Medicine (Baltimore) DOI: 10.1097/md.0000000000024868 sha: 6f096ee6e5d4e0756524f4a88c15c5ca83447b06 doc_id: 15696 cord_uid: pzdmq2ef BACKGROUND: Ophthalmology authors in mainland China, Hong Kong, or Taiwan were interested in knowing their individual research achievements (IRAs). This study was to evaluate the most cited authors, institutes, and regions in the mainland, Hong Kong, and Taiwan in the field of ophthalmology in the recent 10 years using the hx-index and to display the result with visual representations. METHODS: Using the PubMed search engine to download data, we conducted an observational study of citation analyses in affiliated research institutes and regions (provinces/areas) of all ophthalmology authors since 2010. A total of 19,364 published articles from 22,393 authors in the mainland, Hong Kong, and Taiwan were analyzed. The x-index and the Kano model were complemental to the hx-index in identifying IRAs. A pyramid plot was used to illustrate the importance of the author-weighted scheme (AWS) used in evaluating IRAs in academics. The hx-index combining both advantages of the h and x-index was proposed to assess individual IRAs. Furthermore, we drew: 1. a choropleth map on Google Maps to visualize the differences of IRA among regions and 2. a visual display to present individual hx-indexes. RESULTS: There is a significant rise over time in the number of publications. The top-ranking regions in hx-index were Shanghai (26.82), Guangdong (25.82), and Beijing (25.81). We demonstrated that Dr Wu from Taiwan published 144 articles in PMC and used the example to explain the importance of AWS when IRAs were assessed. CONCLUSIONS: With an overall increase in publications in the field of ophthalmology, contributions assessed by hx-indexes and the AWS should be encouraged and promoted more in the future. A few bibliometric studies have been published in the field of ophthalmology. [1] [2] [3] Despite the h-index [3] being one of the most popular indicators of individual research achievement (IRA), [4] there are 2 main disadvantages: Editor: Andrea Giuseppe Maugeri. All data used in this study are available in Supplemental Digital Content files. The authors have no funding and conflicts of interests to disclose. Supplemental Digital Content is available for this article. The datasets generated during and/or analyzed during the current study are publicly available. 1. coauthors are weighted equally in contribution to the article bylines [6] [7] [8] and 2. the integer nature of the h-index making it very hard to differentiate the IRA among groups. [9] We were motivated to use these novel approaches (i.e., AWS and modified h-index) to evaluate IRAs for ophthalmology authors in mainland China, Hong Kong, or Taiwan. Visualizations of results are commonly included in bibliographic analyses. [10] [11] [12] [13] However, none of the bibliometric studies have displayed IRAs on a dashboard for better understanding and detailed examination of the IRAs with a user-friendly interface. Visualization is a potential area of improvement in bibliometric studies. Three questions were of interest: The study is exempt from review and approval by the research ethics committees because it did not involve any patient records. 1. An authorship-weighted scheme (AWS) was used in the previous articles [8, 14, 15] to quantify contributions of individual authors with the definition of total weights equal to 1.0 for each publication. More importance is given to the first (primary) and the last (corresponding or supervisory) authors while assuming that others (the middle authors) made smaller contributions. [1, [16] [17] [18] 2. The hx-index shown in formula (1) is derived from the hindex and allow better discrimination in the form of decimal places; [9] it is defined by rh denoting the ratio (=citations/ publications on the x-core of the x-index = ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi max i ði  c i Þ p , where all of the cited papers are denoted by c i at the i-th publications sorted in descending order) based on the x-core publications and the citations. [17] For instance, an author whose h-index=2 and has an x-index with publications and citations of 3 and 1 has an hx-index of 2.25 (=2 + (1/3)/(1 + 1/3)). This hx-index is the first 1 proposed in the literature so far, and the idea was inspired by previous studies. [18, 19] From formula (1), it can be seen that the hx-index is used to distinguish authors with the same h indexes. In other words, the formula rank the authors with the same h indexes by looking at the impact factors (=citations/publications on the xcore of the x-index) in order to overcome the integer nature of the h-index, which would have made it hard to differentiate the IRAs among entities. [9] 2.3. Representations of the research results 2.3.1. Choropleth maps. The term "choropleth map" was raised by John Kirtland Wright in 1938. [20] The most famous example of CM used was on the results of the 2000 US presidential election. [21] Other examples included showing the disparities in health outcomes across areas involved with dengue outbreaks, [22, 23] disease hotspots, [24] and the Global Health Observatory (GHO) maps on major health topics. [25] 2.3.2. Kano diagrams. The Kano model is developed based on a theory of product development and customer satisfaction in 1984 by Professor Noriaki Kano, [26] who classified products or items into 3 main categories of quality: basic requirement, onedimensional quality, and excitement (aka. wow) feature. Graphs are made with the satisfaction perceived by customers on Axis Y and the accomplishment achieved by providers on Axis X. In this study, we attempt to demonstrate the use of the Kano diagram to characterize the feature of authors using the hx-index in bubble and x-core publications and citations on axes X and Y, respectively. A productive author will be illustrated using the pyramid plot comparing the feature of IRAs with AWS and non-AWS. Visual representation on a dashboard was developed to present individual IRAs in this study. All figures but the pyramid are shown by author-made modules in Excel (Microsoft Corp). We created pages of HTML with Google Maps used. All relevant h-index information on the entities can be linked to dashboards on Google Maps. The overall impact factor is 3.97 (=76895/19364), as shown in Table 1 . There was a significant rise over time in the number of publications, referring to statistics of each region in Table 1 . The top 3 regions in publication number were Shanghai, Beijing, and Guangdong, with the proportion being of 12.87%, 12.71%, and 12.41%, respectively. The top 3 regions in hx-index were Shanghai (26.82), Guangdong (25.82), and Beijing (25.81), as shown in Figure 1 . The top 30 authors are shown in Figure 2 using the Kano diagram. It is worth noting that the article [27] cited 34 times was authored by Dr Wu and his/her colleagues from the Department of Ophthalmology Chang Gung Memorial Hospital, Linkou (Taiwan). The article will instantly appear on PMC when the bubble is clicked, and the publication is selected in Figure 2 . Moreover, we noticed an individual author Dr Wu (Taiwan), on PMC, who published 46 articles since 2004. The importance of AWS when IRAs were assessed is present in Figure 3 , where we can see the author's impact factor increased from 6.5 to 8.9. The hx-indexes identified by either AWS or non-AWS are substantially different because the weighted hx-index will be smaller due to both weighted publications and citations being less than the non-AWS ones. The hx-index for Dr Wu is 7.64, as shown in Figure 4 . It is worth mentioning that the citations and publications have been weighted by the AWS [8, 14, 15] we proposed in this study. Readers are invited to click on the link [28] to see the details about the hxindex for Dr Wu on Google Maps. In this study, there was a significant rise over time in the number of original research published by ophthalmology authors in mainland China, Hong Kong, and Taiwan. Citations were not considered in the case. Similar to choropleth maps that provide a better interpretation of the disparities in health outcomes across countries/areas, [29] the hx-index in Figure 4 helps us understand the IRA for an individual author. [28] There are other features in this study. First, the hx-index with decimal places can complement the original h-index to increase the discrimination power [9] for identifying the IRA characteristics and rankings of a given group. The second feature is the application of the Kano model [26] to interpret the attributes for one's IRA using visual representations. Particularly, the dashboard-type display allows us to see details of the bibliometric indices by scanning the QR-code and clicking on the entity of interest on Google Maps. Readers are invited to see the number of citations for each author in Figure 2 by clicking the bubbles. The reasons for using x-index on 2 axes in Figure 4 are 1. to closely correlate to h-index; [19] and 2. because it was newly developed in 2018, and despite being a simple and easy-to-use metric in comparison to others, the disadvantage of using h-index has been raised. [19] For example, an h-index of 5 means that a scientist has published 5 papers with at least 5 citations each. [10] The h-index Table 1 Publications with first authors in China, Hong Kong, and Taiwan. 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Total % Citations IF Shanghai 84 130 152 166 206 273 302 342 363 474 2492 12.87 10766 4.32 Beijing 106 134 178 194 239 284 279 303 352 392 2461 12.71 9610 3.90 Guangdong 99 130 164 158 194 236 269 324 361 468 2403 12.41 9940 4.14 Taiwan 113 102 94 105 182 256 259 273 288 383 2055 is little affected in those with a high volume of low-impact papers or authors with only a few high-impact articles. [10] A high number of citations or publications were often neglected. [30, 31] The x-index was thus used to complement the h-index to clearly interpret one's feature toward either citation-oriented or productivity-oriented. The hx-index shown on the Kano diagram ( Fig. 4) is novel and innovative in showing the author's IRAs on a dashboard. The third feature is the dashboard of the Kano diagram combined with the hx-index on Google Maps, which is more difficult to create using the traditional BibExce software. [32] The pyramid plot (Fig. 3) for displaying author publications and citations is unique and innovative in comparing the non-weighted and weighted AWS colored bars. [33] Although our analysis provides significant findings, several potential limitations were noticed, and may encourage further research. First, this study only focused on authors in China, Hong Kong, or Taiwan. The results cannot be generalized to other areas and countries. Second, certain biases might have occurred during citation extraction because of the number of citations increasing over the years. Namely, the IRA might differ if the time periods and the citation sources of the data are disparate. Third, many authors work for multiple departments, such as in university, medical school, and affiliated hospital. Only the units listed first were included in this study. The results of hx-index in comparison in Figures 3 might be biased if we were to apply the authorweighted scheme. [8, 14, 15] Fourth, although our proposed hxindex can be easily applied to many other disciplines for comparison of IRAs, many statistical software do not provide such an approach to their users. A simple and useful hyperlink was provided to readers to display the hx-index on a dashboard [28] and arrange their citations in descending order on their own in the future. Finally, although the hx-index is considered useful and applicable in nature, the comparison of the difference in hxindex between groups should be used in cautions due to the hxindexes not always following a normal distribution. The bootstrapping method [34] [35] [36] was recommended to readers for comparison among groups. The hx-index and the Kano models can complement the original h-index in identifying the various IRA characteristics among groups. The bootstrapping method that allows estimation of the sampling distribution for almost all statistic data using random sampling methods with accuracy (as defined by 95% CI) is recommended in future studies when hx-indexes were compared among departments or institutes. We highly recommend the 3 features used in this study, AWS, hx-index, and the Kano diagram, to be applied in the future, not just limited to ophthalmology publications. Trends in authorship of articles in major ophthalmology journals by gender Publication trends in corneal transplantation: a bibliometric analysis Theme trends and knowledge structure on choroidal neovascularization: a quantitative and co-word analysis An index to quantify an individual's scientific research output H-index in medicine is driven by original research Fair ranking of researchers and research teams Quantifying coauthor contributions Applying an author-weighted scheme to identify the most influential countries in research achievements on skin cancer: observational study A comparative analysis of the application of hindex, g-index, and a-index in institutional-level research evaluation Visual analysis of coronavirus disease 2019 (COVID-19) studies based on bibliometrics Use of log-scaled crowded visual acuity charts in clinical studies regarding amblyopia Comparative study of scientific publications in ophthalmology and visual sciences in Argentina Visual exploration of landmarks and trends in the medical informatics literature Whether article types of a scholarly journal are different in cited metrics using cluster analysis of MeSH terms to display: a bibliometric analysis Using the Kano model to display the most cited authors and affiliated countries in schizophrenia research Trends in authorship of articles in major ophthalmology journals by gender Further evidence for adjusting for multiple authorship Using Google Maps to display the pattern of coauthor collaborations on the topic of schizophrenia: a systematic review between 1937 and 2017 A novel bibliometric index with a simple geometric interpretation Problems in Population Mapping in Notes on statistical mapping, with special reference to the mapping of population phenomena Diffusion-based method for producing density-equalizing maps Dengue outbreaks and the geographic distribution of dengue vectors in Taiwan: a 20-year epidemiological analysis Recognizing spatial and temporal clustering patterns of dengue outbreaks in Taiwan Dot map cartograms for detection of infectious disease outbreaks: an application to Q fever, the Netherlands and pertussis /2/23 archived from the original reviewed Attractive quality and must-be quality The prevalence of primary angle closure glaucoma in adult Asians: a systematic review and meta-analysis The hx-index shown on Google Maps Choropleth map legend design for visualizing the most influential areas in article citation disparities: a bibliometric study The h'-Index, effectively improving the h-Index based on the citation distribution The e-index, complementing the h-index for excess citations. The e-index, complementing the h-index for excess citations Analyzing bibliographic data to visualize representations DYTGhGsStmU-MKzOECxQ2kJEglfouO_2aQ?fbclid=IwAR2SMJF-pnZ7dRDXzy8VgqPW0fzMZ0CIyGDNmtVPtsnDVOABx7WqfHT gyNE Evaluating the research domain and achievement for a productive researcher who published 114 sole-author articles: a bibliometric analysis Bootstrap methods: another look at the jackknife Using the bootstrapping method to verify whether hospital physicians have different h-indexes regarding individual research achievement: a bibliometric analysis The use of bootstrapping method to compare research achievements for ophthalmology authors in the US since Medicine (2021) 100:8 www.md-journal