Review of literature, steps in literature review, systematic review, narrative review.

1. Review of Literature
Dr. Usha (PT)
Assistant Professor

2. Introduction
• Fink has defined research literature review as a
“systematic, explicit and reproducible method for
identifying, evaluating, and synthesizing the existing body
of completed and recorded work produced by researchers,
scholars and practitioners.”
• Reviewing the research literature means identifying and
interpreting what is known about a topic.

3. • A literature review contains a critical analysis and the
integration of information from a number of sources, as
well as a consideration of any gaps in the literature and
possibilities for future research.
• NOTE: A literature review is not an annotated
bibliography in which you summarize briefly each
article that you have reviewed.

4. Difference between Annotated Bibliography &
Literature Review
Annotated Bibliography Literature Review
• Comments on the relevance and
quality of the information.
• Sources are analyzed separately
• The source is indicated at the
beginning of each section
• Sources are listed alphabetically
• Literature review establishes a relationship
between different sources and highlights gap
in knowledge.
• Information from different sources are
analyzed together.
• The sources are listed at the end of the
document, as a bibliography.
• Sources ate integrated together according to
relevance

5. • High-quality literature reviews base their findings on
the evidence from controlled experimentation and
observation.
• They rely on the researcher's original studies for
information rather than on other people's interpretations
of the results. Editorials and testimonials are usually
excluded from the review itself because they are
subjective and prone to bias.

6. Literature reviews are used for the following
reasons:
• To write proposals for funding or for degrees
• To describe and explain current knowledge to guide professional practice
• To identify effective research and development methods
• To identify experts to help interpret existing literature and identify unpublished
sources of information
• To identify funding sources and works in progress
• To satisfy personal curiosity

7. Importance of Literature Review
• Identification of a research problem & development or refinement of
research questions.
• Generation of useful research questions or projects/activities for he
discipline.
• Orientation to what is known & not known about an area of inquiry to
ascertain what research can best contribute to knowledge.
• Determination of any gaps or inconsistencies in a body of knowledge.
• Discovery of unanswered questions about subjects, concepts or
problems.
• Determination of a need to replicate a prior study in different study
settings or different samples or size or different study populations

8. Continued…
• Identification of relevant theoretical or conceptual framework for
research problems.
• Identification or development of new or refined clinical interventions to
test through empirical research.
• Description of the strengths & weaknesses of design/methods of inquiry
& instruments used in earlier research work.
• Development of hypothesis to be tested in a research study.
• Helps in planning the methodology of the present research study.
• It also helps in development of research instruments.
• Identification of suitable design & data collection methods for a research
study.

9. Primary, Secondary and Tertiary Literature
1. Primary literature
• The primary (1°) literature comprises all scientific literature that presents
new scientific data or ideas. In general, this encompasses all papers that
present novel scientific research, but also may include literature reviews,
perspectives and analyses that advance new concepts and viewpoints about
data generated by others.

10. 2. Secondary literature
• Secondary (2°) literature comprises summaries of results and
ideas from the primary literature written for an audience of
scientists with some understanding of the topic.
• Since sources of information in 2° literature are always cited,
these articles are excellent places to begin researching a topic.

11. 3. Tertiary literature
• The tertiary (3°) literature is generally written for a nonscientific
audience or for scientists in other disciplines. Generally sources
of information in these articles are not cited, or only a
bibliography of related readings is included. E.g. Science
magazines.

12. Sources of Literature Review

13. Resources
of
literature
review
Electronic
database
Journals
Conference
papers
Books &
Theses
Magazines
&
newspapers
Encyclopedia
&
dictionary
Research
Reports

14. Online Search for Literature Reviews-
Electronic Sources
• Computer-assisted literature search has revolutionized
the review of literature.
• Electronic literature search through web may be very
useful, but sometimes it can be time consuming &
unpredictable because there are many website & web
pages that can lead to information overload &
confusion.

15. • General literature search can be conducted through
search engines like Yahoo (www.yahoosearch.com),
Google (www.google.com), MSN search, Lycos,
WebCrawler, Alta Vista, or Excite.

16. Electronic Databases in Medical Sciences
• Several websites or databases are available online such as:
• Google scholar
• Cochrane library
• PubMed
• Web of Science

17. Scholar Google
• This was created as a tool to gather scholarly literature on the
web. From one place, students have the ability to search for
peer-reviewed papers, theses, books, abstracts and articles from
academic publishers, professional societies, preprint
repositories, universities and other scholarly organizations.

18. Cochrane Collaboration Web site (http://www.cochrane.org).
• The Cochrane Collaboration is an international nonprofit and
independent organization, dedicated to making up-to-date,
accurate information about the effects of health care readily
available worldwide.
• It produces and disseminates systematic reviews of health care
interventions and promotes the search for evidence in the form
of clinical trials and other studies of interventions

19. The Cochrane library
• Although reviews are available in PubMed, for systematic
reviews and meta-analysis, Cochrane library is a much better
resource. The Cochrane library is a collection of full length
systematic reviews, which can be accessed for free in India.
• It is immensely helpful in finding detailed high quality research
work done in a particular field/topic

20. • PubMed Central
• It is perfect for those studying anything related to healthcare or
science. PubMed Central is operated by the National Center for
Biotechnology Information, a division of the U.S. National Library of
Medicine. The database contains more than 3 million full-text journal
articles. It’s similar to PubMed Health, which is specifically for health-
related research and studies, and includes citations and abstracts to more
than 26 million articles.
• Medline
• Web of Science

21. PubMed
• PubMed is currently the most widely used as it contains over 23 million
citations for biomedical literature and has been made available free by
National Center for Biotechnology Information (NCBI), U.S. National
Library of Medicine.
• However, the availability of free full text articles depends on the sources.
Use of options such as advanced search, medical subject headings (MeSH)
terms, free full text, PubMed tutorials, and single citation matcher makes
the database extremely user-friendly.
• It can also be accessed on the go through mobiles using “PubMed Mobile.”
• One can also create own account in NCBI to save searches and to use
certain PubMed tools

22. MEDLINE (Medical Literature Analysis & Retrieved
System Online)
• MEDLINE is the U.S. National Library of Medicine® (NLM)
premier bibliographic database that contains more than 25 million
references to journal articles in life sciences with a concentration on
biomedicine. A distinctive feature of MEDLINE is that the records
are indexed with NLM Medical Subject Headings (MeSH®).
• The NLM provides free access to MEDLINE through PubMed,
available at www.pubmed.com or
http://ncbi.nih.gov/entrez/query.fcgi.
• Generally, abstracts of research articles are provided free of cost;
some of the full-text copies are also freely available.

23. Search Strategy in Electronic Databases
• Search strategy is the key to online databases as it depends on
search process and keywords used to extract the relevant
information in a short time.
• Usually all the databases have advanced search options that
provides easy way to use Boolean operators, title/abstracts,
Mesh terms, PICO search etc.

24. Searching With Boolean Operators
• Literature review searches often mean combining key words and other
terms with words such as and, or, and not. These three words are called
Boolean operators.
• AND- Use AND to retrieve a set of citations in which each citation
contains all search terms. For e.g. Diabetes AND exercises
• OR- Use OR to retrieve citations that contain one of the specified terms.
For e.g. Diabetes OR exercises
• NOT- Use NOT to exclude terms from your search. For e.g. Diabetes
NOT exercises
• Be careful when using NOT because you may inadvertently eliminate
important articles.

25. Review of research literature can be summarized
into a seven step process:
(i) Selecting research questions/purpose of the literature review
(ii) Selecting your sources
(iii) Choosing search terms and running the search
(iv) Applying practical screening criteria
(v) Applying methodological screening criteria/quality appraisal
(vi) Doing the review
(vii) Synthesizing the results.

26. A research literature review - Seven tasks
1. Selecting research questions- A research question is a
precisely stated question that guides the review.
2. Selecting bibliographic or article databases, Web sites, and
other sources- A bibliographic database is a collection of articles,
books, and reports that can provide data to answer research
questions. The database is usually accessed online. The
bibliographic databases of interest in research reviews often contain
full reports of original studies. Other sources for literature reviews
include experts in the field of interest, the Web, and the reference
lists contained in articles.

27. 3. Choosing search terms.
Search terms are the words and phrases that you use to
get appropriate articles, books, and reports. Search
terms are based on the words and concepts that frame
the research questions.

28. 4. Applying practical screening criteria
Preliminary literature searches always yield many articles, but
only a few are relevant. You screen the literature to get at the
relevant articles by setting criteria for inclusion into and
exclusion from the review.
Practical screening criteria include factors such as the
language in which the article is printed, type of article (journal
article, clinical trial), date of publication, and funding source.

29. Organizing The Research Literature
• When the relevant articles are found they are organized
systematically for further use and they should be
organized in a way that they are easily available and
accessible.
• For this, bibliographic software is essential.
• Programs, such as EndNote, ProCite, BibTex,
Bookeeper, Zotero, and Mendeley, have many features
beyond serving as a virtual file cabinet that can store
many articles.

30. 5. Applying methodological screening criteria
Methodological criteria include criteria for evaluating
scientific quality.
6. Doing the review
Reliable and valid reviews involve using a standardized form
for abstracting data from articles, training reviewers (if more
than one) to do the abstraction, monitoring the quality of the
review, and pilot testing the process.

31. 7. Synthesizing the results
• Literature review results may be synthesized descriptively.
Descriptive syntheses are interpretations of the review's
findings based on the reviewers' experience and the quality
and content of the available literature. A special type of
synthesis-a meta-analysis involves the use of statistical
methods to combine the results of two or more studies.

32. Synthesize the Results- Report on current knowledge; justify the need for research; explain research findings;
describe quality of research
Produce Descriptive Review- Primarily qualitative synthesis of results Perform Meta-Analysis- Statistical combination of results
Do the review- add hand searches of references to online searches
Pilot Test the Reviewing Process
Train Reviewers (if more than one)
Apply Methodological Quality Screen- Research design; sampling; data collection; interventions; data
analysis; results; conclusions
Apply Practical Screen- Content covered; years searched; language; setting, sample, interventions, and
outcomes studied; research design
Choose Search Terms- Monitor Quality Ensure reliability and accuracy of review
Select Bibliographic Databases and Web Sites
Select Research Questions

33. Types of Literature Review Designs

34. 1. Narrative Review
2. Systematic Review
3. Meta Analysis
• Selective review of the literature that broadly covers a specific topic.
• Doesn’t allow strict systematic methods to locate and synthesize articles.
• Quantitatively combines the results of studies that are the result of a
systematic literature review.
• Capable of performing a statistical analysis of the pooled results of relevant
studies.
• Utilizes exacting search strategies to make certain that the maximum extent
of relevant research has been considered.
• Original articles are methodologically appraised and synthesized.

35. Writing Literature Review

37. Writing of literature review involves three steps:
1. Introduction
2. Structure/ Body
3. Conclusion

38. 1. Writing Introduction
While writing the introduction, following steps should be taken
in consideration:
• Define or identify the general topic, issue, or area of concern,
thus, providing appropriate context for reviewing the literature.
• Point out overall trends in what has been published about the
topic or conflicts in theory, methodology, evidence, &
conclusion or gaps in research, or a single problem or new
perspective of immediate interest.

39. 2. Writing Body
• Following measures need to be undertaken while writing the body of
the literature.
 Group research studies & other types of literature (reviews, theoretical
articles, case studies) according to common denominators such as
qualitative versus quantitative approaches, conclusions of authors,
specific purposes or objectives, chronology, & so on.
 Summarize individual studies or articles with as much as or as little detail
as each merits according to its comparative importance in the literature,
remembering that space denotes significance.
 Assist the reader with strong ‘umbrella' sentences at the beginning of
paragraphs, signpost throughout, & brief ‘so what’ summary sentences at
intermediate points.

40. 3. Writing Conclusion
• The points to be taken care of in the conclusion are as follows:
 Summarize major contributions of significant studies & articles
to the body of knowledge under review, maintaining the focus
established in the introduction.
 Evaluate the current ‘state of the art’ for the body of knowledge
reviewed, pointing out major methodological flaws or gaps in
research, inconsistencies in theory, & finding & areas or issues
pertinent to future study.
 Conclude by providing some insight into the relationship between
central topic of the literature

41. Points to be considered for literature review
• Be specific, succinct and be selective
• Focus of current topics
• Ensure evidence for claims
• Focus on sources of evidences
• Account of contrary evidences
• Avoid abbreviations and jargons
• Simple & accurate sentence structure
• Organization of literature review
• Referring original source, reference citation

42. Summary Tables
• Useful to prepare as such tables provides a quick overview that
allows the reviewer to make sense of a large mass of
information.
• The tables could include columns with headings such as:
• Author, year
• Type of study, Sample and Design, Data collection approach
• Participants characteristics/criteria, Intervention
• outcome measures
• Key findings/ Results

43. e.g. of review summary table

44. References
• Fink A. Reviewing the Literature: Why? For Whom? How?. Conducting research
literature reviews: From the internet to paper. Sage publications. 4th ed. 2019;1-36. ISBN
978-1-4833-0103-7
• National Library of Medicine. MEDLINE®: Description of the Database. Available from:
https://www.nlm.nih.gov/bsd/medline.html (accessed 1st May 2020).
• Poojary SA, Bagadia JD. Reviewing literature for research: Doing it the right way. Indian
journal of sexually transmitted diseases and AIDS. 2014;35(2):85.
• Researching Information in the Scientific Literature. Biology 106 Spring, Information
Research. 2003;1-10. Available from: http://w3.marietta.edu/~biol/introlab/infores.pdf
(accessed 30th April 2020)

45. Thank You