Scientometrics, the quantitative measurement and analysis of science, has been used to investigate the impact of research publications and other research outputs. In recent years, a scientometric indicator called h-index has gained popularity and recognition in the assessment of research output.
Aspiring scientist and researcher need to constantly be reminded to research a lot, publish a lot more and keep on writing scientific papers. One of the ways to be motivated to work harder and to get better is to know performance. H-index is one way to measure a researcher’s performance. H-index is increasingly used to provide information on the scholarly output in connection with a researcher’s career advancement or award of financial assistance.
What is the h-index? H-index stands for Hirsch index. First introduced by Jorge E. Hirsh in 2005, it is a relatively simple way to calculate and measure the impact of a scientist. The h-index is a measure of an individual’s scientific research output. According to Hirsch, “A scientist has index h if h of his/her Np papers have at least h citations each, and the other (Np − h) papers have no more than h citations each”. The h-index is a small number with a big impact.
How is h-index calculated? The h-index is computed through a plot based on the distribution of citations received to the publications of a researcher. An individual has an index of h, if h papers have at least h citations each. This index translates the impact (the number of citations) and the scope (the number of papers) of a scientist’s work into a straight number. For example, if your h-index is 11, it means that you have 11 papers that have been cited at least 11 times. You may have more papers, suppose 24 papers, only 11 of these papers are cited at least 11 times by other researchers, indicating that other 13 papers have 10 or fewer citations. The h-index will reach 12, only if 12 papers receive a minimum of 12 citations.
The following is the calculation method:
To determine the h-index of the above researcher, organize articles in descending order, based on the number of times they have been cited. Thus, he has twenty-four papers that have been cited 37, 35, 30, 28, 27,21,17, 17, 17, 16, 15,10 and 4 times, o times (paper 14 to 24) the individual’s h-index would be 11. The first paper 37, gives us a 1 – there is one paper that has been cited at least once, the second paper gives a 35, there are two papers that have been cited at least twice, the third paper, 30 and all the way up to 11 with the eleventh highest paper –the remaining thirteen papers have no effect in this case as they have been cited less than eleven times
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Key h-index tools
One should cite the database source from which the h-index was derived. It depends on which database you use: Web of Science (Thomson Reuters), Scopus (Elsevier) or Google Scholar. Web of Science and Scopus collect and organize citation counts and can calculate an individual’s h-index. Likewise, Google Scholar collects citations and calculates and author’s via Google Scholar Citation. However, each source may determine a different value of the h-index for each individual.
Each database considers only those citations in the journals listed in each of the databases. The Web of Science, as mentioned earlier, is not an open access database. Scopus allows viewing your only h-index (without Scopus account). The Google Scholar searches all web-based information both peer and non-peer reviewed literature, which results in considerably higher h-indices. In general, it is found that Google Scholar gives a higher h-index for the same researcher when compared to other two databases. Google Scholar is the only one of the three that is freely accessible to the general population. One can easily create Homepage of Google Scholar citation by signing in Gmail account that automatically calculates and updates h-index and its metrics.
Citations to papers mean that someone used your work or thought it was relevant to mention in the context of their own work. Academician especially young researchers are always favourable towards metrics that make them look good. By keeping track of h-index one can have an idea of how well you have done in your research domain. Despite a few limitations, there is now enough evidence to show that the use of the h-index has become popular and acceptable.