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Medicine: Writing a Literature Review

What is the purpose of the literature review?

A literature review, as part of a thesis or for any other publication, should demonstrate your knowledge of the research has been conducted in the past and should place your research into that context. A thesis is an original and significant piece of work that adds to the body of knowledge in a particular field. A literature review can have a number of purposes within a thesis. These include:

  • demonstrating and clarify your understanding of your field of research;
  • identifying patterns and trends in the literature;
  • identifying gaps in the literature in order to seek new lines of inquiry;
  • identifying similarities and differences in previous research and so place you work in perspective;
  • justifying your own research;
  • increasing your breadth of knowledge of your subject area;
  • identifying seminal and influential published works in your field;
  • identifying relevant journals, publishers and conferences in your field;
  • providing the intellectual context for your own work, enabling you to position your project relative to other work;
  • identifying experts working in your field (a researcher network is a valuable resource);
  • carrying on from other researchers.

You can find more information and resources from the Library:

Document your search strategy

It's a really good idea to document your searches so that you (or someone else) can reproduce them at a later date, and so your methods are open and transparent. Write down where you've searched, when you searched and what you searched, and how you combined your terms and selected the results.

Setting up a personal account in databases you frequently visit will really help with saving and documenting your searches. Once you sign in, you can save and organise individual records, and also save your search history which can be re-run, recorded or refined later. It's usually pretty obvious how to set up an account - click Sign In, or Log In or My Account, or check the help pages of the database you are using.

For more details about documenting your searches, have a look at the Document your search strategy section of the Systematic Review library guide.

For some great examples of how to document your searches, from the PICO to combining keywords, check out this eBook chapter: Foster, M. J., & Jewell, S. T. (2017). Identifying the studies: Case studies. In M. J. Foster & S. T. Jewell (Eds.), Assembling the pieces of a systematic review: A guide for librarians (pp. 99-123). Rowman & Littlefield.

Your search strategy

Here are some steps to follow which will help you work out your search strategy:

1.  Consider putting your research question into a search framework, such as PICO

2.  From there, identify the 2-4 main concepts you need to search. (You won't need to use every element of the PICO. Often there is no C (Comparison) and the Outcome will come out of the results of your search).

3.  Brainstorm keywords and phrases as synonyms for each concept. (This will be an ongoing process as you learn more about your subject and do more reading). Remember to consider the following:

  • scientific terms as well as common terms
  • alternative spellings (US v UK)
  • culturally specific terms
  • abbreviations, acronyms and plurals

4.  Consider phrase searching (usually " ") and truncation symbols (most often *) to make your searching more efficient. (Some databases use different symbols and there are other techniques. Check our Database Help guide for specific instructions).

5.  Once you've come up with as many specific terms as you can find, join them with boolean operators:

  • Taking one concept at a time, connect each term or phrase (synonym) with OR.
  • Then connect these now big groups representing each concept with the AND operator to see where all the concepts overlap.

6.  Now consider the limits of your search and apply them. This may include such refinements as date of publication, geographical area, language, type of study. Do your search first, and then limit the final set of results.

Using a database thesaurus

Most databases in the sciences have a subject headings list or thesaurus attached. This is a way indexers assign standard labels to articles that are on similar topics. From your point of view, it can make searching much easier because if you miss a synonym for a particular concept, it should be covered by the subject label it has been assigned.

Best practice in searching encourages the use of both keyword searching and thesaurus searching as part of your search strategy.

For a demonstration on how to to do this, see Advanced Searching in CINAHL and Advanced Searching in Medline.

Each specific database has its own thesaurus, using terms familiar in that discipline. Medline uses MeSH (Medical Subject Headings), CINAHL uses CINAHL headings, and EmCare uses EMTREE. For this reason, searching across multiple databases is not effective with subject headings. If you repeat a search in different databases, you can re-use the same keywords, but you will have to use the appropriate thesaurus terms for that specific database.

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