The Impact of Prefaces on Impact Factors

Okay, one more post on prefaces to special sections/collections.

One version of the preface is to simply cite all of the papers in the special section with a sentence or two about its contribution to the field. I see two reasons in favor of this style, but several against it as well. For one, this is a nice summary for a reader to quickly learn about the content of the papers without having to read all of the abstracts. Plus, it offers a hyperlinked one-click connection from the preface article to the specific research articles, which is a convenience to the reader.

An argument against this style of preface is that it generates gratuitous self-citation, artificially inflating the journal’s citation metrics. Let’s take a look at the numbers. Regarding Impact Factor, nearly all prefaces are published the same year as the papers in the collection, so they do not influence the Impact Factor at all (see my earlier post on this calculation).  In my quick look at several of them, not all prefaces actually cite all of the papers in the special collection; some of them simply give the context and motivation for the special collection without a run-down of the specific papers and their main results, while others are long review articles that cite 100+ articles from many years. A preface that cites most/all of the articles in the collection do indeed add to citation counts, even if they do not contribute to IF. For JGR (all sections combined), it isn’t much: the journal’s IF for 2012 was {18,111 citations} / {5706 papers}, and 10-20 extra citations would change the IF only in the third or fourth decimal place.

There is a metric called the Immediacy Index that would be affected by a same-year preface with self-citations.  For all of JGR, these numbers for 2012 are {2087} / {2753}, so adding 10-20 citations to the numerator and one paper to the denominator would change it in the second or third decimal place.  This is a noticeable change but still a small one.  Moreover, the Immediacy Index is not a well-known or widely-publicized metric, so very few actually care that it is affected by a few special collection prefaces.

Another argument against it is that this style of preface is almost never cited. So, in that sense, it negatively contributes to IF. This is a true and legitimate complaint: preface articles are usually poorly cited by others (except for a few outliers, usually the longer “review” style introductions), and so, for the next two years, it adds one to the denominator of the IF calculation but little-to-nothing to the numerator.

The main thing is that a preface should provide something of value to the reader, but the question is, what audience? There are several groups that might find a preface useful, but most notably these two: experts in the specific topic and space scientists outside of the specialty. Both can be served by a well-written preface, and a well-written preface should be something that others could (and should) justifiably cite.

Overall, JGR-Space Physics doesn’t publish very many special sections each year, and it publishes even fewer prefaces, so I don’t think that we need to police the gratuitous self-citation within these articles very closely. However, please make it more than just a listing of the papers in the collection, and please involve the journal editorial board so it isn’t sent back to you for modification before review.


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