Saturday, 17 July 2010

Measuring your scientific productivity and impact on science?

Academics, researchers or the scientists work hard for boosting their research and disseminate it through various channels such as conference presentations and articles, technical reports or journal publications. A question can always be raised that 'how to evaluate the individual's productivity and the impact on science or scientific community'. Whether this should relate with the number of articles he published or the quality of these articles? The one widely accepted measure, though opposed by many, is the hirch factor (h-factor). It is not perfect index but takes into account both the quality and the quantity of individual's publications.

What is h-factor?
The h-factor was first described by a physics Professor, J.E. Hirsch, in a PNAS article in 2005. He defined this as 'a scientist has index h if h of his or her Np papers have at least h citations each and the other (Np-h) papers have <=h citations each'. The aim of this article is not to describe the h-factor in detail but to present views on its application in real life. Detailed explanation of h-factor can be seen in the source article. The h-factor can be computed by using SCOPUS, ISI Web of Knowledge or any other tools such as scHolar index.

How does this relate your scientific productivity and impact?
The citation to your articles is the key for a better h-factor. For example, if you publish 250 articles and one of your article gets cited 250 times or more but among the remaining ones, for instance, only 10 other articles get cited 10 or less times; the h-factor in this case will be only 10. This example explains that if one has to increase his/her h-factor its crucial that the articles published by the individual gets continuous citation.

The citation can be directly related with the quality of the research presented in an article. However, there are contrasting thoughts about this. For example, in some cases you may find that despite having excellent science in an article it does not get citations. There could be several reasons for this, such as the novelty of research and its real-world application, dissemination media (i.e. the quality, popularity and the way of an journal to promote research), the name (and fame) of an individual scientists in a particular research area, selection of an appropriate journal for publication and the way of presenting the research in the article in a fresh, interesting and attracting manner, etc.

Is this fair to compare the scientists working in different disciplines using h-factor?
My answer to this question is 'no'. The reason is that articles in some areas are not very well cited as opposed to others; see a lost of journal impact factors here. For example, the most cited journal in Environmental Sciences and Engineering is having an impact factor of about 5. This is much lower if we consider a example of structural engineering in contrast to substantially higher impact factor journals in neuroscience (about 178). It also means that if one is working in an area of high impact factored journals and manage to publish frequently can have a high h-factor.

What 'numbers' are impressive in Engineering?
My personal view is that if you have a h-index less than 15, your impact could be considered 'average'. This could be 'good' when h-index is between 15 and 25, 'very good' between 25 and 35, excellent between 35 and 50, and outstanding over 50. However, I do not have any strong support to defend this classification except saying that I know few people in the area of Engineering that have h-factor just over 50; they are key people in their fields with outstanding individual contributions.

Concluding remarks
It is probably not the best way to measure individuals productivity and impact but we currently do not seem to have a better index. This number could be good to mention in short biographies or applications that are made for jobs or research grants. The h-factor can not grow over night, it requires time to get your articles cited and consistet efforts from your part to include better science in your articles. However, the important thing which I feel is doing the good science in your articles rather than aiming first for h-factor and then writing the articles.

I hope you will find this article interesting and useful. Please feel free to comment on it, if you have any!