H-index Clarification

The h-index which is also called Hirsch index borrowing the name of a Physicist from California whose name was Jorge E. Hirsch and first proposed H- index in 2005, assesses the impact of a particular scientist in a field of study instead of a journal. It can be defined as a numerical indicator revealing how productive and influential a researcher is. In fact, it is the highest number of researchers that a scientist has published [1]. The researchers commonly use the index in a wide range of disciplines to evaluate the impact of both themselves and others on making the improvement within their field of study [2]. This index for each researcher includes H number of the presented papers which were cited H times. According to Hirsch, a successful scholar should have an index of more than 20, an outstanding scholar should possess an index of 40, and a unique researcher should have an index of 60, after 20 years of doing research and study. He himself has the index of 50 [3]. 

The importance of H index:

• It differentiation factor between the influential researchers and the researchers who have just published a large number of studies.
• It makes a comparison between the researchers who work in the same area.
• It identifies the scholars who deserve to be granted by prizes like Nobel.
• It helps the students to find an advisor for their thesis. Since, if they select an advisor with a high level of the index, they will be bestowed with the authentic letter of recommendation after graduation.
• The individuals who have high H index will be more successful in getting jobs in academic positions competing with a large number of job applicants.

The tools of measuring H-index:

1. Web of knowledge:

In this web, you need to be registered, and it is also called the web of knowledge and a part of ISI database. This can be considered as one of the best tools for measuring H index. And, all of the papers represented by a researcher are taken into consideration.

2. Scopus:

This tool belongs to Elsevier, and like Web of Knowledge, the researchers need to be registered. It provides the information related to the index and statics of the authors to the readers. It is noteworthy that the index of the papers which have been listed since 1995, is considered in this database.

3. Google Scholar

This database belongs to Google and measures the index by making a personal account without paying any money. This database is not as exact as the aforementioned webs since all the papers even the ones published in unreliable journals are taken into account.

The Differences between the mentioned indexes by various tools:

• Time period: This factor is mostly considerable in Scopus. Because, the papers which have been registered after 1995, are regarded, and the papers that have been published before that year, are not taken into consideration.
• The inclusion of the papers: It is probable that sometimes an article is not listed in the database.
• The number of the articles: In Web of Knowledge and Scopus, there is a page for every author in which the information about them is recorded. A paper can be registered just once, and it is not possible to transfer the articles. However, in Google Scholar, there is a possibility of the similarity of the names, and the papers may be registered more than once making problem in measuring index.

References:

1.  http://guides.lib.umich.edu/c.php?g=282982&p=1887449.
2. http://theconversation.com/explainer-what-is-an-h-index-and-how-is-it-calculated-41162.
3. Hirsch, J. E. (2005). An index to quantify an individual’s scientific research output. Proceedings of the National Academy of Sciences of the United States of America, 102 (46), 16569–72. doi :10.1073/pnas.0507655102.

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