how to write a literature review

1. DOING THE LITERATURE REVIEW
SELECTING RESOURCES
Shelly Warwick, MLS, Ph.D.

2. WHY A LITERATURE REVIEW IS
IMPORTANT FOR YOU
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To find out if what you think is an unknown is a
known
To find out if what you think is a known is an
unknown
To find out what approaches others have taken
toward the problem/concept, etc.
Avoid unnecessary duplication of research
Identify key works and information on the subject
Identify methods relevant to your research
To find experts in your field you could contact
Learn terminology

3. WHY A LITERATURE REVIEW IS
IMPORTANT FOR YOUR READERS

Ties your research to previous research –
places it in context
Shows questions/issues/approaches to topic taken
by others
 Supports the reason your research is important
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4. WHEN DO YOU DO THE LIT REVIEW?
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A lit review is helpful
 A) Before you formulate your final topic
 A quick search of the literature – especially
narrative review articles to determine areas
that need further research within your area
of interest
 B) After you focus on a topic
 you will need to do a detailed search of the
literature to make sure you are fully
conversant with current ideas, issues and
methods

5. WHAT LITERATURE SHOULD YOU
SEARCH?
You should focus on peer-reviewed articles
 You can start with narrative reviews that
address your topic
 Then move to articles that report on research
 The type of research articles you will need will
depend on your topic
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6. REMEMBER THE EVIDENCE PYRAMID
Meta Analysis
Systematic Reviews
Randomized Controlled
Trials
Cohort Studies
Case Control Studies
Case Series/Case Reports
Animal Research

7. DIFFERENCES IN STUDY TYPES IN THE
PYRAMID
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Animal Studies – studies using animals not humans
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Case Series and Case Reports – reports of the treatment of individual patients or
a single patient. No use of control group. No statistical validity.
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Case Control Studies – retrospective studies comparing patients with a specific
condition or outcome to those without the condition or outcome to determine
exposures or causes. Can show statistical relationship but not necessarily a
causal relationship.
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Cohort Studies – prospective observational studies of patients already being
treated or who have had exposure. Studied group is often compared to general
population or similar population not treated.
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Randomized Controlled Clinical Trials (RCT) – treatment of real patients under
controlled conditions – including randomization to treatment or no treatment and
blinding of which group the individual is assigned from both the patient and
individual(s) providing follow-up and collecting results.
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Systematic Reviews - based on extensive literature search to identify studies
that focus on a highly defined question. Results summarized according to
predetermined criteria. Not to be confused with Review articles that review the
literature on a topic and are usually not exhaustive.
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Meta-analysis – goes beyond the Systematic Review to combining results of
studies using accepted statistical methodology to produce a single conclusion.

8. USING THE RIGHT TYPE OF STUDY FOR YOUR
TOPIC
Type of
Question
Suggested best type of study
Diagnosis
prospective, blind comparison to a gold
standard
Therapy
RCT > cohort > case control > case series
Prognosis
cohort study > case control > case series
Harm/Etiology RCT > cohort > case control > case series
Prevention
RCT > cohort study > case control > case series
Clinical Exam
prospective, blind comparison to gold standard
Cost Benefit
economic analysis

9. CASTING A WIDE NET
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Most literature reviews would start with Medline
Depending on your topic/type of study you might
expand to:
Raw data from such organizations as the CDC, WHO,
New York City Department of Health and Mental
Hygiene
 White Papers (reports) published by government and
non-government groups, such as those that study or
advocate for those with disease and conditions,
independent study groups such as The Robert Wood
Johnson Foundation (these would not be indexed in
PubMED)
 Treatment Guidelines – AHRQ, National Guidelines
Clearing House
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10. FORMAT OF THE LITERATURE REVIEW
The literature view is a narrative.
 Can list authors by name or refer to studies by
reference numbers
 Example with authors name:
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Colbert and Stewart 7 & 8 find that this mode of
treatment is effective, while Moe, Larry & Curley’s 1 & 5
results are mixed and Abbott & Costello 3-4 find no
efficacy.
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Example without authors names:
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Some studies 7 & 8 find that this mode of treatment is
effective, while others1 & 5 report mixed results and yet
others 3-4 find no efficacy.

11. METHOD TO YOUR MANUSCRIPT
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Literature can also include a review of
publications regarding the method you are
using for your study to:
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Compare and contrast methods used in related
studies and establish the rationale for using the
method you selected.

12. WAYS OF GROUPING STUDIES IN THE
LITERATURE REVIEW
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Can group by
Studies that share similar methods
 Nature of findings (positive, negative, neutral)
 Theories underlying study
 Strength of study (more attention to stronger
studies, but mention of weaker studies)
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13. HINTS ON WRITING STYLE
Use present tense to describe general
principles or results .(e.g. results indicate…)
 Use past tense to describe past findings (As
Colbert‘s 2010 study found ….).
 Try for crisp active sentences.
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14. REMEMBER
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The major purpose of the literature review is to
show why you study is necessary and that the
methods you are using for it are valid.