Journal Cititation Statistics – Inter-Citation – Astronomy
Just as articles form a complex network, where some relationship (like “x cites y”) determines the network topology, journals themselves form a similar network, but with less granularity. It’s a little bit like the “thermodynamics” of the article universe. One big difference between the journal and the article universes is that in the journal universe, there are “loops”: journals cite themselves. You can argue that articles, in some sense, cite themselves too, but this is a flow with a constant amplitude across all nodes, while for journals this is clearly not the case. With journal inter-citation (a measure of “how often is journal X cited by journal Y”) we basically look at the out-degree of the nodes.
In this entry I’ll look at the main astronomy journals (The Astrophysical Journal, The Astronomical Journal, Monthly Notices of the R.A.S. and Astronomy & Astrophysics). For a given publication year and journal, I’ve taken the bibliographies of all articles that appeared and determined what percentage of those citations went where. The results are shown below.
No dramatic changes in a period spanning just over a decade. The strongest citation flow goes back into The Astrophysical Journal. The ApJ Letters were second for a while, but have now been overtaken (by a small percentage) by Astronomy & Astrophysics and the Monthly Notices of the R.A.S.
The two largest citation flows here have very similar amplitudes: one looping back to the journal itself and one to The Astrophysical Journal. The next biggest flow is to A&A, followed by MNRAS. Unlike with ApJ, where A&A and MNRAS has roughly the same amplitude, A&A gets significantly more citations from AJ than MNRAS gets. There are very few citations going from AJ to the Physical Review D.
A&A looks very similar to AJ: again ApJ has roughly the same amplitude as the self-citation flow. MNRAS is the next largest flow. ApJ Letters has roughly the same amplitude as AJ. There is a small, but steadily increasing flow to the Physical Review D.
The largest citation flow is to the ApJ, closely followed (bit significantly smaller by ~5%) by the self-citation flow. The third largest flow is to A&A. It interesting to see that MNRAS has the largest citation flow to the Physical Review D of these 4 astronomy journals. Maybe this is an indicator that this journal has, percentage-wise, the largest cosmology content? (or at least theoretical cosmology)
Clearly, ApJ represents the largest citation flows. It is the most “international” journal: it receives the largest amount of citations from both American and European journals. Perhaps this means that it is easier for a European astronomer to publish in ApJ than for an American astronomer to publish in either MNRAS or A&A? It will be interesting to see how these citation flows differ per discipline.