Sunday, 29 May 2011

History, meaning and relevance of "Impact Factor" - Part 1

The day Eugene Garfield mentioned the pioneering concept of Impact Factor, back in 1955 [1], caused a major scientific fuss and, probably without real intention of doing it so. Triggering the start of a novel competition amongst research scientists, their investigations and the grounding pleas for grants, Eugene Garfield had started something valuable that would survive to our days.  For the first time researchers had been stunned by an "arbitrary" paradigm transfiguring to a "league table" the importance of whatever had been accomplished (by a particular investigation) and the vehicle in which it had been publicised, published, shared, utilised, and most importantly - cited. That day back then, Science Magazine and Eugene had generated a wave of acceptance regarding a Citation Index to be "broadcasted"; a "championship of relevance" concerning researchers' work and the impact caused in the scientific community and/or in the particular field their accomplishments were meant to influence.

The first time the scientific community had the opportunity to recognise the value of a citation index happened 4 years after Eugene's suggestion, with the publication of a Science citation index (see an example on image 3). Suddenly, a straightforward exercise like the weighting of the number of citations a piece of article got from their interested research peers became an invaluable weapon. Or shall we call it the stock market of science? Whatever your personal opinion might be, the truth is that these two words together "Impact Factor"  had produced exactly what is intrinsically suggested by their own organics - they were indeed a factor with great impact,  inevitably transforming science for the years to come and beyond.

But who was this Eugene Garfield and what exactly did this gentleman do that provoked such brainstorming Tsunami, one with such consequences that changed the ways of science proclaiming scientific relevance based on the effect on other authors. Well, I didn't know myself, but his famous words were brought up to a very interesting conversation between myself and a final PhD student from the University of Nottingham, my dear colleague and great scientist Anbalagan Charumathi (expect her interview in this space for very soon... ish). She was the one who presented me to this piece of info I had been [unfortunately] missing for quite a long time. But now, with no further ado, I will summarise and respond in a two parts post to those questions that I myself had regarding this very subject - the Impact Factor:

What means Impact Factor? Impact factor, or abbreviated IF, is a sort of table indicating the average number of citations to articles published in the science and the social sciences domains. Its primary functionality is to reflect an idea of the impact caused by a certain investigation to its particular field.

Who created Impact Factor? As stated previously Eugene Garfield, an american scientist and founder of the Institute for Scientific Information (Philadelphia, Pennsylvania), along with Irving Sher, a biochemist, statistician and linguist [2] (and a former Director of Quality Control, Research and Development) who died in December 19th, 1996, due to a kidney disorder. Sher was also the responsible creator of SYSTABAR - System of coding references and Sherhand (for more please see [2]).

This table offers a selective listing of journals presented by their impact factor back in 2004, citations to everything published in 2004, also including the total number of articles published in both 2002 and 2003 in the given journals. For a bigger picture click on the image.

What does the term Impact Factor imply? A concept is never static or rigid if it needs to adapt to times; in that sense the term Impact factor suffered a soft evolution since the first days of its acceptance by the scientific community.  In a crude way, this term describes the impact caused by a Journal and its Author, having on the number of citations a piece of work obtains, the tool for ranking its importance.

In what is the Journal Impact Factor based upon? Two elements are of great relevance for this journal: 1) the numerator, i.e., number of citations in the current year to items published in the previous 2 years, and 2) the denominator, which is the number of substantive articles and reviews published in the same 2 years.

Is there something that has been thought to improve how the ranking is produced? Yes there is, for example, taking into account longer periods of citations as well as sources, and the previous year's articles (solely). The first idea would make the impact factor less current whereas the second idea "would give greater weight to rapidly changing fields" [1] as recognised on the words of Dr Eugene Garfield.

And that's it for today! I know, I know, it's kind of short. Well... this was just a teaser of what is  in the next article to come. If you are curious about it and you definitely want to know more, just pop in for the second and final part of this enticing issue, as it will be developed in more depth and insight this week, here in The Toxicologist Today.

[1] Garfield, E. (2006). "The history and meaning of the journal Impact Factor". JAMA, 295(1), pp. 91-93.

[2] Garfield, E. (2001). "Recolections of Irving Sher 1924-1996: Polymath/information Scientist Extraordinaire". Journal of the American Society for Information, Science and Technology, 52(14), pp. 1197-1202.

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