exaemplar references and significance of scholarly reviews

Stephen J Bensman notsjb at LSU.EDU
Sun Jan 28 21:01:27 EST 2007

>From my readings I have been able to distill three basic reasons that are
advanced for why review articles are cited more than other articles.
First, there is the theory that review articles are longer, than other
articles, and long articles with many citations are more likely to be cited
than short articles with few citations.  I find this doubtful.  Second,
there is the view that scientists are lazy, and it easier and quicker to
read a review article than to plow through the literature yourself.  Some
persons of the this opinion dismiss review articles as mindless compendiums
of abstracts and feel that citations to review articles are less worthy
than citations to research articles.  And, third, review articles are
authoritative summaries of research that distinguish between the good and
the bad, providing guidance for further research.  The last two are
functional explanations, and I would tend to believe that it is the
functional role of review articles that causes them to be more highly cited
than others.

However, there certainly needs to be a lot more research on this question.


Eugene Garfield <eugene.garfield at THOMSON.COM>@LISTSERV.UTK.EDU> on
01/27/2007 04:59:50 PM

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Subject:    Re: [SIGMETRICS] exaemplar references and significance of
       scholarly reviews

If you export the results of a search in WebofKnowledge into the HistCite
software (e.g. your 1000 hits, then the default result after you request an
historiograph will be the "exemplar references".

I would be cautious in describing the siglificance of review articles in
quch simplistic terms. I don't recall any studies in which there is an
analysis of why people cite reviews. Really good scholarly reviews are a
lot more than mere bibliographic surrogates, though they may be useful in
that respect as well. Interpretative reviews often play a key role in the
historical development of topics. Gene Garfield

-----Original Message-----
From: ASIS&T Special Interest Group on Metrics
[mailto:SIGMETRICS at LISTSERV.UTK.EDU] On Behalf Of Morris, Steven (BA)
Sent: Saturday, January 27, 2007 11:55 AM
Subject: Re: [SIGMETRICS] question


I agree that you'd probably only find a weak correlation between number of
references cited and citations received if you don't distinguish between
the type of paper (review or not) and the way it is used as a reference
(well-cited exemplar reference or not).

In my mind the relation is very much tied to the dynamics of specialty
growth.  In a recent paper [1] I asserted that after a discovery that
prompts the birth of a specialty, there is a period of rapid growth in the
specialty where scientists extend the discovery, and present evidence to
support those extensions. The discovery paper and other early important
papers become heavily cited 'exemplar references' during this growth
period. At the end of the growth period, 'consolidation' review papers
appear that codify and summarize the newly generated base knowledge in the
new specialty. These consolidation papers can become highly cited exemplar
references in the sense that they are cited as summaries of collected base
knowledge. Some of these reviews become highly cited, some don't,  I
suspect it has to do both with timing (written at a point when the newly
generated knowledge was ready to be codified), quality and
comprehensiveness, and perceived authority of the review autho!

Given the growth and exemplar process described above, you'd expect the

1) Discovery papers, written before all the base knowledge in the specialty
is generated, wouldn't cite many references, but would be cited heavily. I
think there is evidence out there that discovery papers tend to have few
references. I heard Kate McCain mention this once at a
conference ;-),   but I don't have a reference to support that.

2) Consolidation papers, written to summarize base knowledge immediately
after initial growth, would cite many references and be cited heavily.
Here, the problem is that only some of the consolidation papers become
exceptionally heavily cited exemplar references (the winning reviews that
provide the first good consolidation of the new knowledge), while others
may just be cited at a 'normal' rate for reviews, which is probably a
greater rate than non-review papers.

Some notes:

1) There is certainly evidence that the mean number of references per paper
increases over time. I've read this in the literature (though I can't
recall where) and I've seen this in all specialty specific data sets where
I've bothered to check it. I think this is function of specialty growth:
The network of base knowledge in the specialty gets more intricate as the
specialty grows and 'fills in the blanks', so authors of later papers have
to cite more 'marker references' (Hargens' term [3]) to describe the
position of the contribution of their papers
in the network of base knowledge in the specialty...

2) There is a correlation between the mean number of references per paper
and the length of the papers. Evidence for this is given by Abt[2]. So any
correlations you find between number of references in the paper and the
number of citations it receives may be related to length of papers.

3) In my experience, I find that the distribution of the number of
references per paper is log normally distributed and that the mode of that
distribution varies from one specialty to another.  Now, this fact totally
baffles me.  What social or cognitive process would cause this
distribution to appear?   Is it tied to the same process that governs
the distribution of length of papers? Some sort of proportional growth
process? It's a mystery wrapped in an enigma!  If you figure out what
generates that log-normal distribution, I'll send you a one pound bottle of
Tupelo honey as a prize....

Some other notes:

If you want to study the correlation of references per paper to citations
received, I suggest the following:

1) Gather specialty-specific collections of papers for your studies. The
heterogeneity in a large multiple-specialty study will totally screw up
the statistics...   You should get  about 1000 papers citing about
20,000 references for each specialty study...
2) Separate your references in the collection into 'exemplar' and
'non-exemplar', you can do this by applying a citation threshold, see [1].
3) Arrange the exemplar references serially by the order of their
appearance in the specialty.  I have some SQL queries I can send you for
doing this.
4) Look for 'discovery' references at the beginning of this sequence, and
'consolidation' references at the end of the sequence.
5) Study the correlation for 6 classes of reference: 1- general references,
2- general references less exemplar references, 3- discovery exemplar
references, 4- consolidation exemplar references, 5- general review
references, 6- general review references less exemplar references.



[1] Morris, S. A., 2005,  "Manifestation of emerging specialties in journal
literature: a growth model of papers, references, exemplars, bibliographic
coupling, cocitation, and clustering coefficient distribution" , JASIST,
56(2) 1250-1273 [2] Abt, H. A., 2000,  "The reference-frequency relation in
the physical sciences", Scientometrics, 49(3), 443-451.
[3] Hargens, L. L., 2000, "Using the literature: Reference networks,
reference contexts, and the social structure of scholarship"  American
Sociological Review, 65(6), 846-865

Steven A. Morris, Ph.D
Electrical Engineer V, Technology Development Group Baker-Atlas/INTEQ
Houston Technology Center 2001 Rankin Road, Houston, Texas 77073
Office: 713-625-5055, Cell: 405-269-6576

-----Original Message-----
From: ASIS&T Special Interest Group on Metrics
[mailto:SIGMETRICS at LISTSERV.UTK.EDU] On Behalf Of Stephen J Bensman
Sent: Saturday, January 27, 2007 8:30 AM
Subject: Re: [SIGMETRICS] question

It is well known that review articles summarizing research receive on the
average more citations than other types of articles.  Your question is
considered in the book below:

Narin, F.  (1976).  Evaluative bibliometrics: The use of publication and
citation analysis in the evaluation of scientific activity.  Cherry Hill,
NJ: Computer Horizons, Inc.

Here Nariin write:

CHI (Narin, 1976, pp. 183-219) developed its "influence" method in a report
prepared for the National Science Foundation.  In this report it criticized
Garfield's impact factor as suffering from three basic faults (p. 184).
First, although the impact factor corrects for journal size, it does not
correct for average length of articles, and this caused journals, which
published longer articles such as review journals, to have higher impact

My guess is that you would find no or low correlation between length of
references and number of citations, but, if you used a chi-squared test of
independence,  you a strong positive association with review articles
dominant in the high reference/high citation cell.  As usual,It would be
best to do this test with well-defined subject sets than globally to avoid
the influence of exogenous subject variables.  However, Narin seems to have
been of a different opinion in respect to correlation, so you might look at
what he did.


Ronald Rousseau <ronald.rousseau at KHBO.BE>@listserv.utk.edu> on 01/27/2007
07:33:34 AM

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Subject:    [SIGMETRICS] question

Dear colleagues,

Is there a positive correlation between the length of a reference list of a
publication and the number of citations received? Is this true (or not) in
general, i.e. considering all types of publication? And what if one only
considers 'normal articles', this is when reviews and letters (and other
communications) are not taken into account?

Can someone point me to a reference?



Ronald Rousseau
KHBO (Association K.U.Leuven)- Industrial Sciences and Technology
Zeedijk 101    B-8400  Oostende   Belgium
Guest Professor at the Antwerp University School for Library and
   Science (UA - IBW)
E-mail: ronald.rousseau at khbo.be
web page:  http://users.telenet.be/ronald.rousseau

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