Archive for the ‘Citations’ Category

RSS discussion paper on model-based ranking of journals, using citation data

2015-04-07

This paper has been around on arXiv for quite some time.  Now, having survived various rounds of review — and having grown quite a bit as a result of reviewers’ requests! — it will be discussed at an Ordinary Meeting of the Royal Statistical Society on 13 May 2015 (just follow this link to the recent Allstat announcement, for instructions on how to contribute to the RSS discussion either in person or in writing).

Here is the link to the preprint on arXiv.org:

Statistical modelling of citation exchange between statistics journals by Cristiano Varin, Manuela Cattelan and David Firth.

(Note that the more ‘official’ version, made public at the RSS website, is an initial, uncorrected printer’s proof of the paper for JRSS-A.  It contains plenty of typos!  Those obviously will be eliminated before the paper appears in the Journal.)

The paper has associated online supplementary material (zip file, 0.4MB) comprising datasets used in the paper, and full R code to help potential discussants and other readers to replicate and/or experiment with the reported analyses.

fig4

Figure 4 from the paper (a ranking of statistics journals based on the Bradley-Terry model)

The paper’s Summary is as follows:

Rankings of scholarly journals based on citation data are often met with skepticism by the scientific community. Part of the skepticism is due to disparity between the common perception of journals’ prestige and their ranking based on citation counts. A more serious concern is the inappropriate use of journal rankings to evaluate the scientific influence of authors. This paper focuses on analysis of the table of cross-citations among a selection of Statistics journals. Data are collected from the Web of Science database published by Thomson Reuters. Our results suggest that modelling the exchange of citations between journals is useful to highlight the most prestigious journals, but also that journal citation data are characterized by considerable heterogeneity, which needs to be properly summarized. Inferential conclusions require care in order to avoid potential over-interpretation of insignificant differences between journal ratings. Comparison with published ratings of institutions from the UK’s Research Assessment Exercise shows strong correlation at aggregate level between assessed research quality and journal citation ‘export scores’ within the discipline of Statistics.

R and citations

2011-06-25

We’re hosting the international useR! conference at Warwick this summer, and I thought it might be interesting to try to get some data on how the use of R is growing. I decided to look at scholarly citations to R, mainly because I know where to find the relevant information.

I have access to the ISI Web of Knowledge, as well as to Google Scholar. The data below comes from the ISI Web of Knowledge database, which counts (mainly?) citations found in academic journals.

Background: How R is cited
Since version 0.90.0 of R, which was released in November 1999, the distributed software has included a FAQ document containing (among many other things) information on how to cite R. Initially (in 1999) the instruction given in the FAQwas to cite

When R version 1.8.1 was released in November 2003 the advice on citing R changed: people using Rin published work were asked to cite

The “2003” part of the citation advice has changed with each passing year; for example when R 1.9.1 was released (in June 2004) it was updated to “2004”.

ISI Web of Knowledge: Getting the data
Finding the citation counts by searching the ISI database directlydoes not work, because:

  1. the ISI database does not index Journal of Computational and Graphical Statistics as far back as 1996; and
  2. the “R Core Development Team” citations are (rightly) not counted as citations to journal articles, so they also are not directly indexed.

So here is what I did: I looked up published papers in the ISI index which I knew would cite R correctly. [This was easy; for example my friend Achim Zeileis has published many papers of this kind, so a lot of the results were delivered through a search for his name as an author.] For each such paper, the citation of interest would appear in its references. I then asked the Web of Knowledge search engine for all other papers which cited the same source, with the resulting counts tabulated by year of publication.

It seems that the ISI database aims to associate a unique identifier with each cited item, including items that are not themselves indexed as journal articles in the database. This is what made the approach described above possible.

There’s a hitch, though! It seems that, for some cited items, more than one identifier gets used. Thus it is hard to be sure that the counts below include all of the citations to R: indeed, as I mention further below, I am pretty sure that my search will have missed some citations to R, where the identifier assigned by ISI was not their “normal” one. (This probably seems a bit cryptic, but should become clearer from the table below.)

Citation counts
As extracted from the ISI Web of Knowledge on 25 June 2011:

ISI identifier 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Total
IHAKA R
J COMPUTATIONAL GRAP 5 : 299 1996
5 15 18 43 131 290 472 528 435 419 449 378 396 3579
*R DEV COR TEAM
R LANG ENV STAT COMP : 2003
39 123 91 57 39 25 14 388
*R DEV COR TEAM
R LANG ENV STAT COMP : 2004
16 235 421 327 289 187 126 1601
*R DEV COR TEAM
R LANG ENV STAT COMP : 2005
42 397 531 511 445 366 2292
*R DEV COR TEAM
LANG ENV STAT COMP : 2005
5 39 75 41 25 10 195
*R DEV COR TEAM
R LANG ENV STAT COMP : 2006
55 438 849 656 461 2459
*R DEV COR TEAM
R LANG ENV STAT COMP : 2007
92 714 962 733 2501
*R DEV COR TEAM
R LANG ENV STAT COMP : 2008
208 1402 1906 3516
*R DEV COR TEAM
LANG ENV STAT COMP : 2008
7 21 44 72
*R DEV COR TEAM
R LANG ENV STAT COMP : 2009
172 1363 1535
*R DEV COR TEAM
R LANG ENV STAT COMP : 2010
205 205
*R DEV COR TEAM
R LANG ENV STAT COMP :
1 12 14 25 36 81 93 262
Total 5 15 18 43 131 290 528 945 1452 1964 3143 4354 5717 18605

For the “R Development Core Team (year)” citations, the peak appears about 2 years after the year concerned. This presumably reflects journal review and backlog times.

There are almost certainly some ISI identifiers missing from the above table (and, as a result, almost certainly some citations not yet counted by me). For example, the number of citations found above to R Development Core Team (2009) is lower than might be expected given the general rate of growth that is evident in the table: there is probably at least one other identifier by which such citations are labelled in the ISI database (I just haven’t found it/them yet!). If anyone reading this can help with finding the “missing” identifiers and associated citation counts, I would be grateful.

The graph below shows the citations found within each year since 1998.

© David Firth, June 2011

To cite this entry:
Firth, D (2011). R and citations. Weblog entry at URL https://statgeek.wordpress.com/2011/06/25/r-and-citations/.

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The graph shows the citations found within each year since 1998.

[Click on the graph to view it at a larger size.]

Citations to Ihaka and Gentleman (1996) and to R Core Development Team (any year) are distinguished in the graph, and the total count of the two kinds of citation is also shown.