the use of citation counts as indicators of scholarly impact has
well-documented limitations, it does offer insight into what articles
are read and valued. However, one major disadvantage of citation counts
is that they are slow to accumulate. Mike Thelwall has
examined reader counts from Mendeley, the academic reference manager,
and found them to be a useful source of early impact information.
Mendeley reader data can be recorded from the moment an article appears
online and so avoids the publication cycle delays that so slow down the
visibility of citations.
are widely used as evidence to inform estimates of the impact of
academic publications. This is based on the belief that scientists often
cite works that have influenced their thinking and therefore that
citation counts are indicators of influence on future scholarship. In
the UK’s REF2014 research assessment exercise,
11 of the 36 subject panels drew upon citation counts to inform their
judgements of the quality of academic publications, for example by
arbitrating when two expert reviewers gave conflicting judgements.
Citation counts are also widely used internationally for hiring,
promotion, and grant applications and aggregated citation-based
statistics are used to assess the impact of the work of large groups of
scholars in departments, universities and even entire countries. On top
of this, there are many informal uses of citation counts by individual
scholars looking to assess whether their work is having an impact or to
decide which of their outputs is having the most impact.
Image credit: Mendeley Desktop and iOS by Team Mendeley. This work is licensed under a CC BY 2.0 license.
obvious cases where they are misleading and entire fields for which they
are almost meaningless, citation counts can support the onerous task of
peer review and even substitute for it in certain cases where the
volume of outputs is such that peer review judgements are impractical.
At the level of the individual scholar, citation counts can be useful to
indicate whether papers are read and valued. This gives outputs a
visible afterlife once they have been published and helps to identify
avenues of research that have been unexpectedly successful, motivating
future similar work. It also gives scholars a sometimes-needed incentive
to look outwards at the wider community when writing an article and
consider how it might attract an audience that might cite it. Of course,
uncited does not equate to irrelevant and James Hartley has recently listed his rarely cited articles that he values,
which is a useful reminder of this. Nevertheless, even though I have
little idea why my most cited article has attracted interest, the
knowledge that it has found an audience has motivated me to conduct
follow-up studies and to fund PhDs on the subject, whilst dropping lines
of research that have disappointingly flown under the radar and (so
far) avoided notice.
is that they are slow to accumulate. Once an article has been published,
even if someone reads it on the first day that it appears and
immediately uses it to inform a new study, it is likely to be 18 months
(depending on the discipline) before that study is complete, written up,
submitted to a journal, peer reviewed, revised, accepted and published
so that its citations appear in Google Scholar, Web of Science or
Scopus. Uses of citation counts in formal or informal research
evaluations may therefore lag by several years. This delay is a major
disadvantage for most applications of citation counts. There is a simple
solution that is effective in some contexts: Mendeley reader counts
1: Mendeley readers typically appear at least a year before citations
due to delays between other researchers reading a paper and their new
study being published.
is a social reference sharing website that is free to join and acts as a
reference manager and sharer for academics and students. Those using it
can enter reference information for articles that they are reading or
intend to read (and this is what most users do, as shown by Ehsan Mohammadi,
whose PhD focused on Mendeley) and then Mendeley will help them to
build reference lists for their papers. As spotted by York University
(Toronto) librarian Xuemei Li, it is then possible to count the number of registered Mendeley readers for any given article and use it as impact evidence for that article. This reader count acts like a citation count in that it gives evidence of (primarily academic) interest in articles but readers accrue about a year in advance of citation counts, as shown by a recent article (Figure 2 – see also: Maflahi and Thelwall, 2016; Thelwall and Sud, 2016).
Mendeley data is available earlier as scholars can register details of
an article they are reading in Mendeley whilst they are reading it, and
so this information bypasses the publication cycle delays (Figure 1). An
article may even start to accumulate evidence of interest in Mendeley
in the week it is published if people recognise it as important and
immediately record it in Mendeley for current or future use.
2: A comparison between average Scopus citations and Mendeley readers
for articles from journals in the Scopus Transportation category, as
recorded in November/December 2014. Mendeley reader counts are much
higher than Scopus citations for more recent articles, with Scopus
citations lagging by at least 18 months. Citation counts are higher than
reader counts for older articles, probably due to citations from older
articles that were written before Mendeley was widely used. Geometric
means are used because citation counts are highly skewed (data from Maflahi and Thelwall, 2016).
The main drawback is that, at present, anyone can set up multiple
accounts and register as a reader of selected articles, making it
possible to spam Mendeley. For this reason, Mendeley reader counts
cannot be used in the UK REF or any other research evaluation that
includes stakeholders with time to manipulate the outcomes. An
additional limitation is that Mendeley reader counts are biased towards
articles that attract the Mendeley user demographic, which has
international and seniority/age imbalances. It is therefore tricky to use Mendeley for international impact comparisons.
Mendeley readers for an article – just search for it by title in
Mendeley (e.g. try the query ‘Mendeley readership altmetrics for the
social sciences and humanities: Research evaluation and knowledge
flows’) or look for the Mendeley segment within the Altmetric.com donut
for the article (as in this example;
to find a page like this, Google the article and add
‘site:altmetric.com’ to the end of your query). For large groups of
articles, the free Mendeley API can also be used to automatically
download reader counts for large sets of articles via the (also free)
software Webometric Analyst.
If you already have a set of articles with citation counts, then it is
simple to add Mendeley reader count data to it using this software.
the author, and not the position of the LSE Impact Blog, nor of the
London School of Economics. Please review our comments policy if you have any concerns on posting a comment below.
is Professor of Information Science at the School of Mathematics and
Computing, University of Wolverhampton. His research interests include
big data: webometrics, social media metrics, and sentiment analysis;
developing quantitative web methods for Twitter, social networks,
YouTube, and various types of link and impact metrics; conducting impact
assessments for organisations, such as the UNDP. His ORCID iD is: 0000-0001-6065-205X.
Impact of Social Sciences – Mendeley reader counts offer early evidence of the scholarly impact of academic articles