Pitfalls of the novel parameter, n-index

Amir Feily, Reza Yaghoobi

 Department of Dermatology, Jundishapur University of Medical Sciences, Ahvaz, Iran

Correspondence Address:
Amir Feily
Department of Dermatology, Azadegan Street, Imam Khomeini Hospital, Ahvaz
Iran

Sir,

While there are many new indices with interesting, unique attributes to evaluate /rank any researcher, none has been found to be perfect or near perfect. ^[1] We read with interest the view point by Namazi and Fallahzadeh published in the May-Jun 2010 issue of Indian Journal of Dermatology Venerology and Leprology. ^[2] In their paper, the authors considering field variation described a problem that hampers a fair evaluation of scientific performance. To surmount unequal citations in different fields, the authors suggest a novel index: n-index = Researcher′s h-index divided by the highest h-index of the journals of his/her major field of study. Although this is true, one point raised is that some of the authors have got their h-index from their articles in different areas of science.

The most obvious paradigmic example of that is the inventor of n-index Namazi. At this moment the h-index of Namazi is 9 ^[3] and one of his publications that has raised his h-index is "Results of the application of intraoperative mitomycin C in dacryocystorhinostomy." ^[4] Notably, this article has been published in European Journal of Ophthalmology by 13 times citations ^[4] and there is no relationship between above mentioned article and dermatology. Reasonably, it is impossible to divide his h-index by the highest h-index of the journals of his major field of study, dermatology. Similarly being a co-author or being one of the members of a large multi-centric study, being a research associate and co-author of a publication in a journal with a Nobel laureate (with high index - whatever h or n), not related to the area of specialization, will remain as an issue.

It should be pointed out that journals undoubtedly get their h-index from the high quality articles which have been written by influential authors. Accordingly, another criticism raised is the conflict between increasing h-index of the journals of author′s major field of study and decreasing author′s n-index. As an example, well-known authors who have published his/her sublime works in highest h-index journals of his/her major field of study can expect that by increasing citations of his/her articles and journal`s h-index as well, their n-index would have been decreased.

Another criticism raised is that n-index can not be used for author′s publication in multidisciplinary journals. For instance h-index for journal of Nature is 599 ^[5] which is around 6 times more than 103 - the h-index of Journal of American Academy of Dermatology. ^[6] Therefore, for a scientist who has published just 4 but brilliant masterpieces in this journal by more than 4 citations, it would be surely unfair to divide his/her h-index 4 by the h-index of the journal of Nature and to compare with a dermatologist with the same h-index.

However, we agree with Namazi and Fallahzade that field variation creates obstacle to fair evaluation of scientific performance; but given the pitfalls mentioned above, we can neither accept their view point nor advocate that n- index can replace h-index in all proposed indices based on it.

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