"A review of the literature consists of reading, analyzing, and writing a synthesis of scholarly materials about a specific topic...A review of the scientific literature is fundamental to understanding the accumulated knowledge about the topic being reviewed."
Source: Health Sciences Literature Review Made Easy (Garrard 2011).
This handout from The Writing Center at UNC Chapel Hill, walks through the literature review process; from understanding what a lit review is, to constructing a thesis statement, to thinking about how to organize your review.
This brief, easy-to-read article describes different types of literature reviews.
"Literature reviews in the introduction to a report provide readers with an overview of existing evidence, and contribute to the argument for the new study. These reviews are usually only 2 to 4 double spaced pages, and so, only key studies can be cited. The emphasis is on summarizing and evaluating an overall body of evidence."
Source: Polit, D. F., & Beck, C. T. (2012). Nursing research: Generating and assessing evidence for nursing practice. New York: Wolters Kluwer Health | Lippincott Williams & Williams.
"An integrative review is a specific review method that summarizes past empirical or theoretical literature to provide a more comprehensive understanding of a particular phenomenon or healthcare problem...Well-done integrative reviews present the state of the science, contribute to theory development, and have direct applicability to practice and policy."
If you're conducing an integrative review, definitely read this Whittemore and Knafl article. It clearly explains what an integrative review is and how to design and implement one.
"A systematic review involves the identification, selection, appraisal, and synthesis of the best available evidence for clinical decision making. A properly conducted systematic review uses reproducible, preplanned strategies to reduce bias and instill rigor and pools information from both published and unpublished sources...
Systematic reviews are conducted to answer specific, often narrow, clinical questions. These questions are formulated according to the mnemonic PICO addressing: a specific population (P) (such as people traveling long distance), the intervention of interest (I) (e.g., preventive measures for deep vein thrombosis), an optional comparison (C) (such as the standard of care, which may be no intervention), and one or more specific outcomes (such as prevention of deep vein thrombosis)."
For a narrative review as part of a research report, you want to conduct a comprehensive search to identify as many sources as possible on your topic. You'll then choose the key studies to include in your report.
Search health sciences databases (i.e. Cinahl, Medline) for keywords related to your topic. (See the Articles on Your Topic page of this guide for tips and resources).
Having trouble? Make an appointment with a librarian to discuss databases, keywords, and search strategies
When you find a relevant article, use it to identify other potentially relevant articles:
Look at its references to identify other relevant articles that you haven't found.
Reviews that are part of a research report don't usually share their search strategy, but it's still a good idea to take notes to make the process as organized and efficient as possible.
It is important to clearly document search strategies in the methods sections. This lets your readers know exactly how you identified the studies in your review and makes your search replicable. For example:
List the databases you search and the keywords you used
Explain how you used citation searching to identify additional articles
Discuss the exclusion criteria you used
Not every article that comes up in your search will be appropriate for your review. As you examine your search results, come up with specific criteria that makes an article not suitable to be included. Some examples include:
Relevance to your topic (i.e. different meaning of a term, different aspect of your topic, etc.)
Publication type (journals, grey literature, etc.)
Language of publication
The goal is to be as strategic and transparent as possible about your exclusion criteria. Excluding studies from a review increases the risk of bias, so you'll want to choose your criteria carefully and make it explicit in your write-up.
A synthesis matrix helps you compare research articles side-by-side so you can identify common themes and visualize the bigger picture.
This very brief article explains what a synthesis matrix is and how to use one for your literature review:
This book goes into detail about the matrix method, which is a system of organizing the literature review process. Chapters 5 and 6 explain how to set up a synthesis matrix, with an example on pages 157-158.