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What is a ‘‘mapping study?’’
I. Diane Cooper, MSLS, AHIP
See end of article for author’s affiliation. DOI: http://dx.doi.org/10.3163/1536-5050.104.1.013
You are familiar with those short literatu re reviews
in the introduction of research studies. The author
provides a brief background to the study,
highlighting related research. You also know about
review articles in which writers describe a batch of
articles that they have selected. If there were a
‘‘ reliab ility’’ spectr um of review articles, both of
these would be on the low end—not because they are
necessarily inaccurate, but because they were
selected by the writer and may be biased.
On the other end of the spectrum is the systematic
review, which, if done correctly, eliminates (or
greatly reduces) possible bias. So it is felt to be the
most reliable.
These types of reviews deal with the subst ance of
the article’s content. Something is studied, and the
focus is on the results: ‘‘ Here is what we found.’’ The
review discusses the findings.
Mapping studies are also reviews, but they do not
discuss the findings. They are based on the concept
that published articles not only represent findings,
but, indirectly, represent activity related to the
finding. For example, an article that presents
findings of a study at a community center of an
education intervention to improve health represents
not only the study results, but it also represent s that
research on community health education took place.
The article also indicates where the research took
place and, of course, in what journal it was
published. So mapping collects data on kinds of
activity, locations where it occurs, and media where
it is published.
On the spectrum of reliability, mapping, if done
correctly, is on the higher reliability end of the
spectrum but still has some vulnerability: decisions
about ‘‘ core,’’ zones, and limits are arbitrary.
So, what is mapping? It is a review that seeks to
identify, not results, but linkages. Mapping focuses
on characteristics such as where the activity took
place, where the funding came from, and in what
journal or other medium it was presented. Mapping
often focuses on published items but need not; some
mapping studies include oth er media (e.g., books,
newspapers, grant proposals).
Some definitions say mapping follows the flow of
information through publications. The weakness of
this definition is that citations may refer to
established information, such as a labo ratory test
designed years ago; such citations do not represent
flow of information. The information has been sitting
in the researcher’s information bin for years.
‘‘ Mapping’’ also sometimes refers to ‘‘ concept
maps,’’ which are visual tools that organize and
display knowledge in a visual way, such as using
flow charts, graphs, and Venn diagrams.
‘‘ Scoping reviews’’ also track down published
studies but are more similar to systematic reviews.
Compared to systematic reviews, scoping reviews do
focus on findings but do not always have quality as
an initial requirement to be included, and synthesis
of data is typically more qualitative [1].
EXAMPLES OF MAPPING
Mapping research is performed in many disciplines.
The method is sometimes called a systematic
mapping review.
Have you ever wondered about the distribution of
social content in Wikipedia? A mapping study found
that the highest percent of articles, 30%, dealt with
culture and the arts. The next 3 topics, in order, were
‘‘ people and self,’’ geography and place, and society
and social sciences. Health and fitness was eighth,
taking up 2% of the social content articles [2]. This
study was led by Aniket Kittur, an expert in human-
computer interaction, social computing, and social
networks.
Have you ever wondered about agricultural
research in India? (You might, if you were a
government policy advisor.) Most publications are
on plants of economic interest, and the greatest
subtopic is ‘‘ Pests, pathogens and biogenic diseases
of plants,’’ according to a mapping study by Subbiah
Arunachalam, an editor and scientometricist. The
76 J Med Lib Assoc 104(1) January 2016
OF INTEREST
professor added, ‘‘ Thi s macroscopic analysis not
only provides an inventory of India’s publications,
but also gives an idea of endog enous research
capacity. If appropriately linked with public policy, it
can help restructure the nation’s research priorities’’
[3].
If you wondered about the state of research about
physical activity programs for adolescents, you
would appreciate another recent mapping study. It
found that most researchers used randomized
controlled studies (about 80%), and most studies
used self-report, although a third used pedometers
or accelerometers [4]. They also found that research
on the topic had increased recently.
MAPPING IN LIBRARY SCIENCES
Have you ever wondered about where clinical
laboratory science and medical technology literature
is published? A typical library science mapping
study was done by Frances Delwiche. She found that
the Cumulative Index to Nursing and Allied Health
Literature was the only databa se wit h complete
coverage of the key journals. Delwiche said her
study’s goals were ‘‘ to identify the predominant
format of literature used in this field, the currency of
the literature most frequentl y used, the core journals
of the field, and the level of indexing coverage of the
core journals by the major bibliographic databases.
The results will serve as a valuable aid to librarians
responsible for collection development in the field’’
[5].
In library science, many mapping studies focus on
finding journals that publish the greatest number of
related papers. These journals would be of higher
priority for purchasing. The list may also be
instructive to faculty, for example, to scan tables of
contents.
HOW DOES IT WORK?
Here is an example to illustrate the literature
mapping process. This is an imaginary exercise, and
the data are made up. Suppose you want to map the
literature of pediatric podiatr y re search. What this
means is, you want to describe where the published
research is coming from.
First, you identify the major journals related to
pediatric podiatry. You ask people who use pediatric
podiatry information what they think are the key or
most important research journals for them. There are
other ways to find major journals: For example,
impact factors might be used; however, a journal’s
impact factor may be due to its publication of articles
not related to pediatric podiatry. Regardless of the
method used to select major journals, the process is a
judgment call. Usually, you decide there are a
handful of major journals.
Then you search the major journals for every
article related to pediatric podiatry publi shed in the
past 3 years. You find 100 articles. From the se
articles, you extract all the references that they cite.
This becomes your database. Each article has about 7
end-of-article reference citations, so you have 700
items.
For each of the 700 items (citations) in your
database, you have or can find the name of the
journal it was published in (its origin), the location of
the researchers, and the source of funding. You can
group your items by any characteristic you wish.
Perhaps you want to know where the research is
coming from: you group by location of the
researchers. Perhaps you want to know where the
funding comes from: you group by funding source.
We are librarians, so we group by the title of the
journal.
You then have a database, a list. Each row will
have the journal name and the number of articles in
that journal that were cited by articles related to
pediatric podiatry in the major journals. For
example, the Journal of Podiatry might be at the top of
the list, as it was the source journal for 100 citations
in the major journals. The next highest number might
be 50, associated with the Annals of Podiatry. The
third might be Pediatric Orthopedics (a surprise to
you) with 25 citations. These 3 journals accounted for
175 or one quarter of the tota l. You want to find the
journals that are sources for much of the work, which
is usually about a third of the database items, so you
add 4 more journals to your list until you reach 233
total citations (1/3 of 700). You label these 7 journals
as in Zone 1 for journals that provide important
information as defined by having many articles cited
in a major journal.
Now, you want to define Zone 2. You go down
your list until you find journals that were sources for
another 233 citations. There will undoubtedly be
more than 7 journals, following Bradford’s Law of
Scattering (Figure 1). Bradford’s Law does not
provide a proscriptive formula: journals can be
moved in and out of Zone 1 to make the map fit the
What is a ‘‘ mapping study?’’
J Med Lib Assoc 104(1) January 2016 77
pattern. In this case, there are 14 more journals, and
you label them as being in Zone 2.
You can now advise librarians that two-thirds of
important literature related to pediatric podiatry will
likely be in journals that are in the 21 (7þ14) journals
that are in Zone 1 or Zone 2 of your list.
If you had done the sorting by researcher location,
you might have said that most of the research came
from large Midwestern states or something like that.
If you had done the sorting by funding source,
you might have said that most of the funding came
from the National Institutes of Health, and second
was the Pediatric Podiatry Foundation.
The Nursing and Allied Health Resources Section
mapping review process is describ ed in a separate
article (See Perryman: ‘‘ Mapping Studies,’’ this
issue).
ACKNOWLEDGMENT
Thank you to Shelley Arvin, Cunningham Memorial
Library, Indiana University, for contributing to this
manuscript.
REFERENCES
1. Armstrong R. ‘Scoping the scope’ of a Cochrane review.
J Public Health. 2011;33(1),147–50.
2. Kittur A, Chi EH, Suh B. What’s in Wikipedia: mapping
topics and conflict using socially annotated category
structure. In: Proceedings of the SIGCHI Conference on
Human Factors in Computing Systems. (CHI 2009).
ACM, New York, NY, 1509–12. DOI: http://dx.doi.org/10.
1145/1518701.1518930.
3. Arunachalam S, Umarani K. Mapping agricultural
research in India: a profile based on CAB Abstracts 1998.
Current Science. 2001 Oct;81(8):896–906.
4. Bush PL, Bengoeshea EG. What do we know about
how to promote physical activity to adolescents? a
mapping review. Health Educ Res. 2015;30(5):756–72.
5. Delwiche FA. Mapping the literature of clinical
laboratory science. J Med Lib Assoc. 2003 Jul;91(3):303–
10.
AUTHOR’S AFFILIATION
I. Diane Cooper, MSLS, AHIP, jmlaeditorbox@
gmail.com, Editor-in-Chief, Journal of the Medical
Library Association
Figure 1
Bradford’s Law of Scattering
Cooper
78 J Med Lib Assoc 104(1) January 2016