Other Indices of Journal Importance

Here are some other metrics of a journal’s significance. They are in no particular order.  This is a longer post but I hope worth the time to read it.

I compare JGR’s value for each of these against the 16 journals that I listed in the last post as “the usual suspects” of where space physicists publish.  This isn’t entirely fair, because JGR is far more than just space physics (JGR-Space is only one of the 7 sections of JGR) and other journals also go into other disciplines (like ApJ and ApJ-Letters are mostly astrophysics, not space physics).  Still, I’m making the comparisons anyway, just for fun.

Total Cites:  This is pretty straightforward; it’s the total number of citations that year to papers published in that journal, regardless of the year in which they were published.  While it certainly measures a journal’s impact on the field, this value definitely favors bigger and older journals.  For 2012, JGR had 161,862 total cites.  This is second of the 16 journals (behind ApJ).

Five-Year Impact Factor: this is just like the standard 2-year Impact Factor, except that values for 5 years go into both the numerator and denominator.  This is probably a better indicator of importance than the standard 2-year Impact Factor because JGR papers tend to have a citation half-life of ~10 years (I’ll have a later post on this issue).  The 2012 5-Year Impact Factor for JGR is the number of citations in 2012 to JGR papers published in 2007-2011 (47,339), divided by the number of papers published in those same years (13,351), for a value surprisingly close to its 2-year Impact Factor value… 3.55 (4th of the 16).

Immediacy Index: ratio of the number of citations to papers published that year to the number of papers published that year.  This number is often less than one for space physics journals, but a few are above unity (specifically, Solar Physics and ApJ).  It should favor journals with a fast submission-to-publication time, but interestingly JGR’s score is higher than that for GRL.  For 2012, JGR published 2753 papers and there were 2087 citations to those papers during that same year, so its Immediacy Index was 0.76 (5th of the 16).

Journal Self-Cites: this is a simple-enough calculation, it is the number of citations that year to the journal’s papers that came from the journal itself.  This is a rough measure of the importance of a journal to the discipline (the higher the number, the more that papers in the field are published in that journal).  It could also mean that the journal is isolated in its field.   For 2012, the number of self-cites was 33,940, which is 20% of the Total Cites (the percentage is 6th of the 16).

Two-Year Self-Cites: A related value to Self-Cites, this is the number of self-cites contributing to that journal’s Impact Factor.  For 2012, that was 5165, which is 28% of the 18,110 citations used in the Impact Factor calculation (the percentage is 5th of the 16).

Eigenfactor Score:  this is kind of like the computer rankings of college football teams for the BCS, because it is like the Five-Year Impact Factor but then weighs the citations in the numerator according to the number of times the citing journal was cited. The actual weightings are nonlinear and self-citations are removed from this calculation.  Typical scores are below 0.5, except for journals like Science and Nature that are about 1.5. This score typically favors larger publications.  For 2012, JGR’s Eigenfactor Score was 0.345 (2nd of the 16).

Article Influence Score:  This is an attempt to calibrate the Eigenfactor Score by the number of papers in the entire discipline.  The Eigenfactor Score is divided by a function of the papers in the journal and the papers across all journal, and then the scores are normalized to an average value of one within the journal’s category (for JGR, that’s “Geosciences – Multidisciplinary”).  For 2012, JGR’s Article Influence Score was 1.47 (3rd of the 16, but this perhaps isn’t a fair comparison because of the category-specific normalization).

Just for completeness, here is the one we’ve already covered…the Impact Factor: based on the previous 2 years, JGR’s 2012 Impact Factor was 3.17 (5th of the 16).

Across all of these measures of importance, JGR fairs very well.


8 thoughts on “Other Indices of Journal Importance

  1. Pingback: The Impact of Prefaces on Impact Factors | Notes from the JGR-Space Physics Editor-in-Chief

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