A literature review surveys scholarly articles, books and other sources (e.g. dissertations, conference proceedings) relevant to a particular issue, area of research, or theory, providing a description, summary, and critical evaluation of each work. The purpose is to offer an overview of significant literature published on a topic.
A systematic review is a review of literature focused on a research question that identifies, appraises, selects and synthesizes all quality research evidence relevant to that question. Systematic reviews of high-quality randomized controlled trials are crucial to evidence-based medicine.
An understanding of literature or systematic reviews and how to implement them in practice is important for professionals involved in research and health care. Systematic reviews are not limited to medicine and are common in other sciences where data are collected, published in the literature, and an assessment of methodological quality for a precisely defined subject would be helpful.
Step 1: Frame questions for a review
The problems addressed by the review should be in clear, structured questions before beginning review work. Once the review questions have been set, modifications to the protocol should be allowed only if alternative ways of defining the populations, interventions, outcomes or study designs become apparent.|
Step 2: Identify relevant work
The search for studies should be extensive. Multiple resources should be searched without language restrictions. The study selection criteria should flow directly from the review questions and be specified a priori. Reasons for inclusion and exclusion should be recorded.
Step 3: Assess the quality of studies
Study quality assessment is relevant to every step of a review. Question formulation (Step 1) and study selection criteria (Step 2) should describe the minimum acceptable level of design.
Selected studies should be subjected to a general critical appraisal and design-based quality checklists (Step 3). These detailed quality assessments will be used for exploring heterogeneity and informing decisions regarding suitability of meta-analysis (Step 4). In addition they help in assessing the strength of inferences and making recommendations for future research (Step 5).
Step 4: Summarize the evidence
Data synthesis consists of tabulation of study characteristics, quality and effects as well as use of statistical methods for exploring differences between studies and combining their effects (meta-analysis). Exploration of heterogeneity and its sources should be planned in advance (Step 3). If an overall meta-analysis cannot be done, subgroup meta-analysis may be feasible.
Step 5: Interpret the findings
Be careful of bias. Exploration for heterogeneity should help determine whether the overall summary can be trusted, and, if not, the effects observed in high-quality studies should be used for generating inferences. Any recommendations should be graded by reference to the strengths and weaknesses of the evidence.
Similar to primary research, development of the literature review has four stages:
Literature reviews should include the following elements:
In assessing each piece, consider:
Definition and Use/Purpose:
A literature review may be a chapter of a thesis or dissertation, or may be a self-contained review of writings on a subject. In either case, its purpose is to:
The literature review itself, however, does not present new primary scholarship.
What is a Literature Review?
A literature review discusses published information in a particular subject area, time period or research. It can be a simple summary of sources but usually combines a summary and a synthesis of material.
Ten Steps for Writing a Literature Review:
1. Define a topic and audience:
- must be interesting to you
- an important aspect of the field
- a well-defined issue
2. Search and Re-Search the Literature:
- keep track of databases and search items
- keep a list of papers and pdfs,
- use a management system: Refworks, EndNote, Mendeley
- define criteria for exclusion
- use reviews
3. Take NOTES while reading
4. Choose the type of review to write:
5. Keep the review focused, but broad interest. (could discuss other disciplines affected)
6. Be Critical and consistent:
A reader should have an idea of
- The major achievements in the reviewed field.
- The areas of debate.
- The outstanding research questions.
7. Find a logical structure.
Try using a mind-map to draw a conceptual scheme of the review.
8. Make use of feedback. Can be peer-reviewed or someone reading a draft.
9. Include your own relevant research but be objective.
10. Be Up-to-date, do not forget older studies.
Original by Marco Pautasso. PLOS. July 2013, vol. 9, issue 7.
AVOID these traps:
Questions: Your Librarian, Susan Koskinen, email@example.com
Annual Reviews critically reviews significant primary research literature. Each article provides a gateway to the essential primary research literature referenced within each topic.
BIOSIS Previews: enter your search, use limit to "Literature Types" and Review (if available).
Coverage: 1926 - present
Cochrane Database of Systematic Reviews: enter your search, limit to review.
Coverage: date varies | Some full text |
Embase: enter your search, left menu, use limit to "Literature types" and select reivew / apply.
Embase is a key resource for systematic reviews and researching evidence-based medicine. Coverage: dates vary
PubMed: enter your search, select filter - 'review'. Includes Systematic Reviews search limit, and peer review. (Guide: HTML | PDF).
Covers: 1946 - present