A literature search is a planned & organized search for relevant literature on a specific topic. Writing a review of the existing literature on a topic is key part of research conducted in medicine. Literature searches are conducted using databases, library catalogues, & the internet. Literature searching requires time, planning & knowledge of database searching techniques.
Remember that searching:
This guide will provide you with
The process of writing a literature review involves the following steps:
Define your question. Is it Feasible, Interesting, Novel, Ethical, & Relevant?
Formulate your search using keywords, thesaurus terms & boolean logic strategy.
Select relevant databases & other internet sources to search
Start your search; keep track of your results from each database.
Evaluate your results & refine your search terms & logic if necessary based on relevancy of results to your question.
Define your search question
Start by Identifying a broad topic & consider whether it is Feasible, Interesting, Novel, Ethical, & Relevant.
Turn your topic into a question; a clearly-defined question will:
Formulate your search A concept table may help you gather terms for your search. Use it to:
The PICO method helps you derive an answerable question to focus your search for resources on your topic of interest..
You may also wish to consider different question formulations which may be better suited to your research topic:
For full details, please see
Booth, A. et al. (2019) Formulating questions to explore complex interventions within qualitative evidence synthesis. BMJ Global Health v.4:e001107. Available at: https://gh.bmj.com/content/4/Suppl_1/e001107
The number, type & combination of terms you use in your search will depend on both your question & the objective of your research. A search can not be both specific & sensitive. Your job as a researcher is to find the balance.
A specific search (also called precise or narrow search)
A sensitive search (also called a broad search)
Tips to increase Sensitivity
- instead of CANCER and CHEMOTHERAPY and NAUSEA --> search CHEMOTHERAPY and
- instead of CHEMOTHERAPY and NAUSEA --> search (chemotherapy OR alemtuzumab OR
cisplatin OR Hexalen) AND (nausea OR vomiting OR emesis)
Tips to increase Precision
- instead of TYLENOL and FEVER --> search TYLENOL and FEVER and RANDOMIZED
- instead of CHEMOTHERAPY and NAUSEA --> search ''CHEMOTHERAPY INDUCED NAUSEA AND
Literature searches often produce a large number of citations & require use of several databases.
Good search practice includes keeping a search diary or a document including details of your search strategy to allow others to reproduce your steps & get the same results.
Record your search strategies by logging details on
Download the citations you have retrieved to a reference manager &/or excel spreadsheet to deduplicate citations if necessary.
Databases allow you to do different kinds of searches.
Basic keyword search: similar to a library catalogue or Google search where you use whatever keywords you think describe your topic.
Subject heading search: use the thesaurus terms (also known as controlled vocabulary) of the database to find all articles tagged with specifically assigned subject headings.
Combined keyword & subject heading search: for advanced research, use combined searching to ensure retrieval of current and relevant resources to support your research. Start with your own basic keywords as concepts but also find out what the thesaurus term in the database is for that concept and combine them.
Using both Keyword & Thesaurus terms in a database search will help you in the following ways.
Subject Search Tutorials
|Medline Complete & Cinahl||MeSH / Cinahl Headings||
Once you have formulated your question, isolated your concepts & decided on your keywords &/or thesaurus terms, combining terms is the next step:
How to combine terms for best results: use boolean operators AND, OR, NOT
When you use keywords to augment your search strategy, databases have advanced tricks to save you time & help you include as many related terms as possible.Always check database help for symbols used.
Truncation for Keyword Searching is a search technique where possible word endings are replaced by a symbol. The database will search for all possible variations of the word.
Frequently used truncation symbols include the asterisk (*), a question mark (?) or a dollar sign ($)
Wildcards for Keyword Searching In addition to truncation, wildcards can be used in keyword searches. The wildcard is represented by a question mark ? or a hash tag # placed in the middle of a word to account for possible different spellings of the same word.
Use the ? wildcard to replace an unknown character in your term so that your search returns all alternate spellings for that word.
Add the # wildcard in your search term where an alternate spelling may contain an extra character. This search finds all citations of the word that appear with or without the extra character.
PubMed is a free web-based interface for searching MEDLINE
Basic Search Tips
Finding a few good articles on a specific topic is quick & easy.
You are looking for articles about chemotherapy & colorectal cancer.
Type your keywords into the search box: PubMed searches for keywords in the article title, abstract & subject headings. Results are automatically sorted by Best match (i.e. most relevant to your terms). Choose from the other DISPLAY OPTIONS to sort according to your needs.
Advanced Search Tips
To run a more complex search select Advanced to:
Ebsco MEDLINE Complete is a user friendly interface for searching all abstracts from the Medline subset of PubMed. MEDLINE uses MeSH (Medical Subject Headings) to index all articles from its select list of 5200+ biomedical journals. Medline Complete provides direct links to full text Medline content available via UNic.
Basic Search Tips
To create a basic search:
1. Enter your terms in the search bar
2. Click on the Search Options and select a specific search mode such as ''Apply related words'' or apply Limiters such as ''Full Text''
3. Click on the Search button and the results display
To conduct a search using MeSH:
Follow the steps descibed on the example below to learn how to search in MEDLINE Complete using MeSH
Advanced Search Tips
In order to run a well-rounded search through EBSCO MEDLINE, this video will walk you through the steps you need to follow
Proximity searching allows you to search based on how closely two or more search terms appear in the search results.
The proximity operators are composed of a letter (W or N) and a number (to specify the number of words).
W# = with
N# = near
IMPORTANT! Different databases use different proximity operators. Check the help menu of the database you're searching to find out what symbols it uses.
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