Wednesday, 11 July 2018

The great Google Citation Purge

Our Vice-Provost for Research and Innovation writes a blog to share thoughts, ideas, and announcements.  I thoroughly approve of his communicating via a blog, of course.  I end up reading what he says more than some other communications from the top that get put on e.g. the University's intranet.  It's a shame that the blog does not allow commenting, as that's an integral part of the ethos and culture of blogs, in my opinion, but okay, it's perhaps not surprising from a blog on a corporately-controlled part of the University website.  At least the thing exists.

Recently, he wrote a pretty extensive post about sharing and advertising one's research.  It is aimed at University of Surrey staff, and so is partly dedicated to our own institutional repository, but its chief recommendation is to use Google Scholar.  I do, and I've been using it for many years.  I posted in 2012 about an annoyance of Google Scholar in that it sometimes seems to forget about citations that it previously knew about.   It has just undergone a such a moment of amnesia.

My most cited paper, as previously judged by Google Scholar is this one.  As I write this post, the commercial subscription citation database ISI Web of Knowledge thinks it's been cited 216 times (making it #3 of all the Phys. Rev. C papers from 2012).  It even has a little trophy logo, calling it a "Highly Cited Paper":


Google Scholar was recently completely on board with this, listing it as my most highly cited paper, but I can't show you a screenshot because it now thinks it is more modestly-cited, at a mere 33 citations:


Based on my past experience, Google Scholar usually knows of many more sources of citation than ISI -- from PhD theses, for example, if they have been posted anywhere online, yet suddenly the number of citations has dropped rapidly.

Anyone know why?