DOING THE LITERATURE REVIEWSELECTING RESOURCESShelly Warwick, MLS, Ph.D.

WHY A LITERATURE REVIEW IS IMPORTANT FOR YOU

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

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

WHEN DO YOU DO THE LIT REVIEW? A lit review is helpful

A) Before you formulate your final topicA 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 topicyou will need to do a detailed search of

the literature to make sure you are fully conversant with current ideas, issues and methods

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

REMEMBER THE EVIDENCE PYRAMID

Animal Research

Case Series/Case Reports

Randomized Controlled Trials

Cohort Studies

Systematic Reviews

Case Control Studies

Meta Analysis

DIFFERENCES IN STUDY TYPES IN THE PYRAMID

Animal Studies – studies using animals not humans Case Series and Case Reports – reports of the treatment of individual

patients or a single patient. No use of control group. No statistical validity.

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.

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.

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.

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.

Meta-analysis – goes beyond the Systematic Review to combining results of studies using accepted statistical methodology to produce a single conclusion.

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

CASTING A WIDE NET 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

FORMAT OF THE LITERATURE REVIEW The literature view is a narrative. Can list authors by name or refer to

studies by reference numbersExample with authors name: 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.

Example without authors names: 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.

METHOD TO YOUR MANUSCRIPT Literature can also include a review of

publications regarding the method you are using for your study to: Compare and contrast methods used in

related studies and establish the rationale for using the method you selected.

WAYS OF GROUPING STUDIES IN THE LITERATURE REVIEW 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)

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.

REMEMBER 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.