​About the size of Google Scholar: playing the numbers

[Enrique Orduña]

Dear Stephen,

First, thank you very much for your critical and fruitful feedback, and for
these studies you recommend us, that we find extremely interesting.
​ ​
In fact,
​the work ​
expressly devoted to Google Scholar
​ is
 cataloged in our
​Google Scholar Digest Bibliography.


It is true that perhaps the word
​ ​
"contains" referred to Google Scholar is not entirely accurate. We know
that Google does not "possess" the documents, it is clear that Google is
“simply” a search engine that serves as a bridge between the documents
(wherever they are deposited, universities, repositories, journals, etc.)
and end users.

In any case, it is true that Google Scholar classifies each record using
its own metadata scheme. Therefore, it is a database of bibliographic
references, which provide access to the document (sometimes the full text,
sometimes a short abstract, sometimes nothing really).

A different question is whether it makes sense or not knowing the size
​ of this set of references​
. And
​at this point
 I disagree with you. It is not a meaningless issue.

Your vision is company-oriented. Obviously Google is a search engine, and
​it ​
wants to provide the best possible result for a given query. And what the
user also wants is to get the best result. We agree.

​Nonetheless,
 ​
as researchers devoted to bibliometrics and webmetrics, we are interested
in a better understanding of the processes
​related to
 scientific communication. And knowing the size and evolution of Google
Scholar is fundamental. Scopus and WoS represent the elite, but sometimes
we
​may ​
want to know the processes
​that
 happen outside the elite, and today this world outside the cream is
represented by Google Scholar, though of course, it does not cover
everything that exists
. And moreover, can we be sure that such cream is not identified by Google
and provided to users as well?​

Thus, of course PageRank (by the way increasingly obsolete) is important
for Google and for
​its ​
users
​ (most of us and increasing)​
, but we raised up other questions apart from the commercial use of the
product, regardless the opacity, that we denounce in our work, and Isidro
Aguillo also comments on in his latest email.

​I look forward to read your ​next working paper about this topic, and
thanks again for your good feedback.

Sincerely,

Enrique



On Thu, Sep 11, 2014 at 8:46 AM, Isidro F. Aguillo <
isidro.aguillo at cchs.csic.es> wrote:

> Adminstrative info for SIGMETRICS (for example unsubscribe):
> http://web.utk.edu/~gwhitney/sigmetrics.html
> Are you talking about Google Scholar?
>
> The useless bibliographic tool that does not allow to extract large data
> sets?
>
> The system that blocked the access to it to your whole organization if you
> try to do it?
>
> Are suffering CAPTCHA?
>
> Is somebody able to talk with them and convince of changing their approach
> to our community?
>
> On 10/09/2014 20:17, Stephen J Bensman wrote:
>
>  Enrique and Emilio.
>
> I read your working paper with great interest as it deals with the same
> topic on which we are doing research here at LSU.  To tell you the  honest
> truth, I had trouble with its basic premise, i.e., that Google Scholar (GS)
> has a given size.  I do not think that it does, and, if it does, it is
> meaningless.  The real problem is what is the size of documentary set that
> is relevant to the search query.
>
>
>
> The WWW and PageRank (the Google search engine) operate within what can be
> called the power-law or Lotkaian domain.  Informetric laws also operate
> within this domain.  On top of that, PageRank operates on what is called
> the probability ranking principle, by which the probability of relevance
> exponentially decreases as the number of inlinks decreases, i.e. below a
> certain point you are dealing with gibberish manufactured by the search
> engine itself.  Therefore, there is a need for left truncation and
> determination of what can be termed the x-min.  Since we are dealing with
> the Lotkaian domain, the x-min marks the point where the asymptote or
> “tail” on the x-axis for the items begins.
>
>
>
> We are dealing with Nobelists, and what we have found is that with
> PageRank the set of relevant documents is conterminous with the
> researcher’s h-index and the “tail” of his GS citations distribution.  In
> other words—whether by serendipity or not—the h-index is an excellent
> estimate of the x-min of a GS citations distribution.  Below that is what
> the Germans would call a “Trummerzone” or rubbish zone largely manufactured
> by the search engine itself.  This conterminous-ness is a validation of
> both the h-index and Google Scholar.  The relevance of the set is also
> proven by the fact that the extreme outliers on the right messing up the
> tail are usually works on the topics for which the Nobelist won the prize.
> Case closed.
>
>
>
> Every field has its statistical problem.  With medical research it is
> right truncation, for every patient has to die before the results are
> really known.  With the WWW and scientometric research, it is left
> truncation.
>
>
>
> If you are interested in how I view how Google Scholar works, you can read
> our working papers at the following URLs:
>
>
>
> http://arxiv.org/abs/1312.3872
>
>
>
> http://arxiv.org/abs/1404.4904
>
>
>
> I hope to post another working paper there next week that will really
> clinch the point.  But who knows?  I may be wrong.
>
>
>
> Respectfully,
>
>
>
> Stephen J Bensman, Ph.D.
>
> LSU Libraries
>
> Lousiana State University
>
> Baton Rouge, LA 70803
>
> USA
>
>
>
>
>
> *From:* ASIS&T Special Interest Group on Metrics [
> mailto:SIGMETRICS at LISTSERV.UTK.EDU <SIGMETRICS at LISTSERV.UTK.EDU>] *On
> Behalf Of *Enrique Orduña
> *Sent:* Wednesday, September 10, 2014 5:15 AM
> *To:* SIGMETRICS at LISTSERV.UTK.EDU
> *Subject:* [SIGMETRICS] ​About the size of Google Scholar: playing the
> numbers
>
>
>
> Adminstrative info for SIGMETRICS (for example unsubscribe):
> http://web.utk.edu/~gwhitney/sigmetrics.html
>
> ​ ​
>
> Dear Colleagues,
>
> The purpose of this mail is to present our latest working paper, deposited
> on July 24, 2014.
>
> http://googlescholardigest.blogspot.com.es/2014/09/about-size-of-google-scholar-playing.html
>
> ​ ​
>
>
>
> We propose the inextricable task of knowing the size of this huge black
> hole looks like Google Scholar (GS). Anyway, as the title of the document (
>
> ​ ​
>
> About the size of Google Scholar: playing the numbers), we have begun to
> make accounts and using 4 different empirical methods we estimate that the
> number of unique documents (different versions of a document are excluded)
> should not be less than 160 million (as of May 2014).
>
>
>
> Regardless of this particular outcome, which is itself significant
> (especially when compared with other scientific databases, and that gives
> us key clues about the amount of scientific knowledge that can be
> searchable, found and accessed to on the web), even more exciting is the
> methodological challenge of this assumption. It has not only forced us to
> devise various techniques for measuring the size of this dark object that
> GS is, but
>
> ​ also ​
>
> applying them we have shed light, again, on various inconsistencies,
> uncertainties and limitations of the search interface tools used by Google.
> In short, we have learned more about what Google Scholar does or does not,
> and we want to share it with you all.
>
>
>
> This research comes at a good time. We are not only almost celebrating the
> 10th anniversary of GS but also hearing some voices (from somewhere in
> Europe…) finally relying on the use of Google Scholar for scientific
> evaluation.
>
>
>
> Now, when empirical studies (
> http://googlescholardigest.blogspot.com.es/p/bibliography.html)
> demonstrate every day that Google Scholar and its derivatives
>
>
>
> a) measure with similar credit to traditional bibliometric indicators,
>
> b) are the most used products by scientists (
> http://www.nature.com/news/online-collaboration-scientists-and-the-social-network-1.15711
> ),
>
> ​ and​
>
>
>
> c) have unfortunately ended up with the competition (Microsoft Academic
> Search is in an unexplained hibernation,
> http://googlescholardigest.blogspot.com.es/2014/04/empirical-evidences-microsoft-academic-search-dead.html
> )
>
> ​ .​
>
>
>
> seems that certain euphoria unleashed. We are pleased, better late than
> never…
>
>
>
> However, without wanting to lower the aroused expectations, we emphasize
> that the problems of Google Scholar for scientific evaluation are not
> technical or methodological (coverage, reliability and validity of the
> measures, records filtering performance…). Seminal limitations are those
> related with:
>
>
>
> a) the ease with which GS indicators can be manipulated
>
> ​
>
> (
> http://ec3noticias.blogspot.com.es/2014/01/google-scholar-wins-ravesbut-can-it-be.htmt
> ),
>
> b) the transience of the results and measures (in many cases difficult to
> replicate stably),
>
> c) the technological dependence on companies that develop tools that come
> and go on the consumer product market (
> http://ec3noticias.blogspot.com.es/2014/04/la-new-new-horizontes.html-bibliometrics
> ).
>
>
>
> Google Scholar enthusiasts are now welcome; meanwhile we will continue
> vigorously in which we already proposed several years ago: to reveal with
> “data”
>
> ​ - ​
>
> and not mere opinions
>
> ​ -​
>
> , the bowels of Google Scholar, and to reveal at the same time their
> strengths and weaknesses. So, like the old serials published, we can only
> promise...TO BE CONTINUED…
>
>
>
> ​ Best,​
>
>
>
> Enrique Orduña-Malea​
>
> ​ Polytechnic University of Valencia​
>
>
>
> ​ ​Emilio Delgado López-Cózar
>
> Universidad de Granada​
>
>
>
>
>
> --
>
> ************************************
> Isidro F. Aguillo, HonDr.
> The Cybermetrics Lab, IPP-CSIC
> Grupo Scimago
> Madrid. SPAIN
> isidro.aguillo at csic.es
> ORCID 0000-0001-8927-4873
> ResearcherID: A-7280-2008
> Scholar Citations SaCSbeoAAAAJ
> Twitter @isidroaguillo
> Rankings Web webometrics.info
> ************************************
>
>
>
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-- 
<http://www.institutoidf.com/> <http://www.institutoidf.com/>



*Enrique Orduña-Malea*
Personal de investigación.
Grupo de Investigación EC3. Instituto de Diseño y Fabricación (IDF).

Universidad Politécnica de Valencia (UPV).

Camino de Vera s/n, 46022 Valencia. Edificio 1H.
Tfo. 96 3879480 (Ext. 79480)
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